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Make core VMA operations internal and testable

RFC PATCH In review Lorenzo Stoakes 4 participants 17 messages Jun 28, 2024 – Jul 3, 2024

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#0 lore raw

v2 cover Make core VMA operations internal and testable

There are a number of "core" VMA manipulation functions implemented in mm/mmap.c, notably those concerning VMA merging, splitting, modifying, expanding and shrinking, which logically don't belong there.

More importantly this functionality represents an internal implementation detail of memory management and should not be exposed outside of mm/ itself.

This patch series isolates core VMA manipulation functionality into its own file, mm/vma.c, and provides an API to the rest of the mm code in mm/vma.h.

Importantly, it also carefully implements mm/vma_internal.h, which specifies which headers need to be imported by vma.c, leading to the very useful property that vma.c depends only on mm/vma.h and mm/vma_internal.h.

This is useful, because we can then re-implement vma_internal.h in userland, stubbing out and adding shims for kernel mechanisms as required, and then can directly and very easily unit test internal VMA functionality.

This patch series takes advantage of existing shim logic and full userland maple tree support contained in tools/testing/radix-tree/ and tools/include/linux/, separating out shared components of the radix tree implementation to provide this testing.

Kernel functionality is stubbed and shimmed as needed in tools/testing/vma/ which contains a fully functional userland vma_internal.h file and which imports mm/vma.c and mm/vma.h to be directly tested from userland.

A simple, skeleton testing implementation is provided in tools/testing/vma/vma.c as a proof-of-concept, asserting that simple VMA merge, modify (testing split), expand and shrink functionality work correctly.

v2:
* Reword commit messages.
* Replace vma_expand() / vma_shrink() wrappers with relocate_vma().
* Make move_page_tables() internal too.
* Have internal.h import vma.h.
* Use header guards to more cleanly implement userland testing code.
* Rename main.c to vma.c.
* Update mm/vma_internal.h to have fewer superfluous comments.
* Rework testing logic so we count test failures, and output test results.
* Correct some SPDX license prefixes.
* Make VM_xxx_ON() debug asserts forward to xxx_ON() macros.
* Update VMA tests to correctly free memory, and re-enable ASAN leak detection.

v1:
https://lore.kernel.org/all/[email protected]/

Lorenzo Stoakes (7):
userfaultfd: move core VMA manipulation logic to mm/userfaultfd.c
mm: move vma_modify() and helpers to internal header
mm: move vma_shrink(), vma_expand() to internal header
mm: move internal core VMA manipulation functions to own file
MAINTAINERS: Add entry for new VMA files
tools: separate out shared radix-tree components
tools: add skeleton code for userland testing of VMA logic

 MAINTAINERS                                   |   14 +
 fs/exec.c                                     |   68 +-
 fs/userfaultfd.c                              |  160 +-
 include/linux/atomic.h                        |    2 +-
 include/linux/mm.h                            |  112 +-
 include/linux/mmzone.h                        |    3 +-
 include/linux/userfaultfd_k.h                 |   19 +
 mm/Makefile                                   |    2 +-
 mm/internal.h                                 |  167 +-
 mm/mmap.c                                     | 2070 ++---------------
 mm/mmu_notifier.c                             |    2 +
 mm/userfaultfd.c                              |  168 ++
 mm/vma.c                                      | 1766 ++++++++++++++
 mm/vma.h                                      |  362 +++
 mm/vma_internal.h                             |   52 +
 tools/testing/radix-tree/Makefile             |   68 +-
 tools/testing/radix-tree/maple.c              |   14 +-
 tools/testing/radix-tree/xarray.c             |    9 +-
 tools/testing/shared/autoconf.h               |    2 +
 tools/testing/{radix-tree => shared}/bitmap.c |    0
 tools/testing/{radix-tree => shared}/linux.c  |    0
 .../{radix-tree => shared}/linux/bug.h        |    0
 .../{radix-tree => shared}/linux/cpu.h        |    0
 .../{radix-tree => shared}/linux/idr.h        |    0
 .../{radix-tree => shared}/linux/init.h       |    0
 .../{radix-tree => shared}/linux/kconfig.h    |    0
 .../{radix-tree => shared}/linux/kernel.h     |    0
 .../{radix-tree => shared}/linux/kmemleak.h   |    0
 .../{radix-tree => shared}/linux/local_lock.h |    0
 .../{radix-tree => shared}/linux/lockdep.h    |    0
 .../{radix-tree => shared}/linux/maple_tree.h |    0
 .../{radix-tree => shared}/linux/percpu.h     |    0
 .../{radix-tree => shared}/linux/preempt.h    |    0
 .../{radix-tree => shared}/linux/radix-tree.h |    0
 .../{radix-tree => shared}/linux/rcupdate.h   |    0
 .../{radix-tree => shared}/linux/xarray.h     |    0
 tools/testing/shared/maple-shared.h           |    9 +
 tools/testing/shared/maple-shim.c             |    7 +
 tools/testing/shared/shared.h                 |   34 +
 tools/testing/shared/shared.mk                |   68 +
 .../testing/shared/trace/events/maple_tree.h  |    5 +
 tools/testing/shared/xarray-shared.c          |    5 +
 tools/testing/shared/xarray-shared.h          |    4 +
 tools/testing/vma/.gitignore                  |    6 +
 tools/testing/vma/Makefile                    |   15 +
 tools/testing/vma/errors.txt                  |    0
 tools/testing/vma/generated/autoconf.h        |    2 +
 tools/testing/vma/linux/atomic.h              |   12 +
 tools/testing/vma/linux/mmzone.h              |   38 +
 tools/testing/vma/vma.c                       |  207 ++
 tools/testing/vma/vma_internal.h              |  882 +++++++
 51 files changed, 3910 insertions(+), 2444 deletions(-)
 create mode 100644 mm/vma.c
 create mode 100644 mm/vma.h
 create mode 100644 mm/vma_internal.h
 create mode 100644 tools/testing/shared/autoconf.h
 rename tools/testing/{radix-tree => shared}/bitmap.c (100%)
 rename tools/testing/{radix-tree => shared}/linux.c (100%)
 rename tools/testing/{radix-tree => shared}/linux/bug.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/cpu.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/idr.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/init.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kconfig.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kernel.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kmemleak.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/local_lock.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/lockdep.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/maple_tree.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/percpu.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/preempt.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/radix-tree.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/rcupdate.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/xarray.h (100%)
 create mode 100644 tools/testing/shared/maple-shared.h
 create mode 100644 tools/testing/shared/maple-shim.c
 create mode 100644 tools/testing/shared/shared.h
 create mode 100644 tools/testing/shared/shared.mk
 create mode 100644 tools/testing/shared/trace/events/maple_tree.h
 create mode 100644 tools/testing/shared/xarray-shared.c
 create mode 100644 tools/testing/shared/xarray-shared.h
 create mode 100644 tools/testing/vma/.gitignore
 create mode 100644 tools/testing/vma/Makefile
 create mode 100644 tools/testing/vma/errors.txt
 create mode 100644 tools/testing/vma/generated/autoconf.h
 create mode 100644 tools/testing/vma/linux/atomic.h
 create mode 100644 tools/testing/vma/linux/mmzone.h
 create mode 100644 tools/testing/vma/vma.c
 create mode 100644 tools/testing/vma/vma_internal.h

--
2.45.1

#1 lore raw

RFC PATCH v2 1/7 userfaultfd: move core VMA manipulation logic to mm/userfaultfd.c

This patch forms part of a patch series intending to separate out VMA logic and render it testable from userspace, which requires that core manipulation functions be exposed in an mm/-internal header file.

In order to do this, we must abstract APIs we wish to test, in this instance functions which ultimately invoke vma_modify().

This patch therefore moves all logic which ultimately invokes vma_modify() to mm/userfaultfd.c, trying to transfer code at a functional granularity where possible.

---
 fs/userfaultfd.c              | 160 +++-----------------------------
 include/linux/userfaultfd_k.h |  19 ++++
 mm/userfaultfd.c              | 168 ++++++++++++++++++++++++++++++++++
 3 files changed, 198 insertions(+), 149 deletions(-)
fs/userfaultfd.c +11 -149
index 17e409ceaa33..31fa788d9ecd 100644
@@ -104,21 +104,6 @@ bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma)
 	return ctx->features & UFFD_FEATURE_WP_UNPOPULATED;
 }
 
-static void userfaultfd_set_vm_flags(struct vm_area_struct *vma,
-				     vm_flags_t flags)
-{
-	const bool uffd_wp_changed = (vma->vm_flags ^ flags) & VM_UFFD_WP;
-
-	vm_flags_reset(vma, flags);
-	/*
-	 * For shared mappings, we want to enable writenotify while
-	 * userfaultfd-wp is enabled (see vma_wants_writenotify()). We'll simply
-	 * recalculate vma->vm_page_prot whenever userfaultfd-wp changes.
-	 */
-	if ((vma->vm_flags & VM_SHARED) && uffd_wp_changed)
-		vma_set_page_prot(vma);
-}
-
 static int userfaultfd_wake_function(wait_queue_entry_t *wq, unsigned mode,
 				     int wake_flags, void *key)
 {
@@ -615,22 +600,7 @@ static void userfaultfd_event_wait_completion(struct userfaultfd_ctx *ctx,
 	spin_unlock_irq(&ctx->event_wqh.lock);
 
 	if (release_new_ctx) {
-		struct vm_area_struct *vma;
-		struct mm_struct *mm = release_new_ctx->mm;
-		VMA_ITERATOR(vmi, mm, 0);
-
-		/* the various vma->vm_userfaultfd_ctx still points to it */
-		mmap_write_lock(mm);
-		for_each_vma(vmi, vma) {
-			if (vma->vm_userfaultfd_ctx.ctx == release_new_ctx) {
-				vma_start_write(vma);
-				vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
-				userfaultfd_set_vm_flags(vma,
-							 vma->vm_flags & ~__VM_UFFD_FLAGS);
-			}
-		}
-		mmap_write_unlock(mm);
-
+		userfaultfd_release_new(release_new_ctx);
 		userfaultfd_ctx_put(release_new_ctx);
 	}
 
@@ -662,9 +632,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs)
 		return 0;
 
 	if (!(octx->features & UFFD_FEATURE_EVENT_FORK)) {
-		vma_start_write(vma);
-		vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
-		userfaultfd_set_vm_flags(vma, vma->vm_flags & ~__VM_UFFD_FLAGS);
+		userfaultfd_reset_ctx(vma);
 		return 0;
 	}
 
@@ -749,9 +717,7 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma,
 		up_write(&ctx->map_changing_lock);
 	} else {
 		/* Drop uffd context if remap feature not enabled */
-		vma_start_write(vma);
-		vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
-		userfaultfd_set_vm_flags(vma, vma->vm_flags & ~__VM_UFFD_FLAGS);
+		userfaultfd_reset_ctx(vma);
 	}
 }
 
@@ -870,53 +836,13 @@ static int userfaultfd_release(struct inode *inode, struct file *file)
 {
 	struct userfaultfd_ctx *ctx = file->private_data;
 	struct mm_struct *mm = ctx->mm;
-	struct vm_area_struct *vma, *prev;
 	/* len == 0 means wake all */
 	struct userfaultfd_wake_range range = { .len = 0, };
-	unsigned long new_flags;
-	VMA_ITERATOR(vmi, mm, 0);
 
 	WRITE_ONCE(ctx->released, true);
 
-	if (!mmget_not_zero(mm))
-		goto wakeup;
-
-	/*
-	 * Flush page faults out of all CPUs. NOTE: all page faults
-	 * must be retried without returning VM_FAULT_SIGBUS if
-	 * userfaultfd_ctx_get() succeeds but vma->vma_userfault_ctx
-	 * changes while handle_userfault released the mmap_lock. So
-	 * it's critical that released is set to true (above), before
-	 * taking the mmap_lock for writing.
-	 */
-	mmap_write_lock(mm);
-	prev = NULL;
-	for_each_vma(vmi, vma) {
-		cond_resched();
-		BUG_ON(!!vma->vm_userfaultfd_ctx.ctx ^
-		       !!(vma->vm_flags & __VM_UFFD_FLAGS));
-		if (vma->vm_userfaultfd_ctx.ctx != ctx) {
-			prev = vma;
-			continue;
-		}
-		/* Reset ptes for the whole vma range if wr-protected */
-		if (userfaultfd_wp(vma))
-			uffd_wp_range(vma, vma->vm_start,
-				      vma->vm_end - vma->vm_start, false);
-		new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS;
-		vma = vma_modify_flags_uffd(&vmi, prev, vma, vma->vm_start,
-					    vma->vm_end, new_flags,
-					    NULL_VM_UFFD_CTX);
-
-		vma_start_write(vma);
-		userfaultfd_set_vm_flags(vma, new_flags);
-		vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
+	userfaultfd_release_all(mm, ctx);
 
-		prev = vma;
-	}
-	mmap_write_unlock(mm);
-	mmput(mm);
-wakeup:
 	/*
 	 * After no new page faults can wait on this fault_*wqh, flush
 	 * the last page faults that may have been already waiting on
@@ -1293,14 +1219,14 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 				unsigned long arg)
 {
 	struct mm_struct *mm = ctx->mm;
-	struct vm_area_struct *vma, *prev, *cur;
+	struct vm_area_struct *vma, *cur;
 	int ret;
 	struct uffdio_register uffdio_register;
 	struct uffdio_register __user *user_uffdio_register;
-	unsigned long vm_flags, new_flags;
+	unsigned long vm_flags;
 	bool found;
 	bool basic_ioctls;
-	unsigned long start, end, vma_end;
+	unsigned long start, end;
 	struct vma_iterator vmi;
 	bool wp_async = userfaultfd_wp_async_ctx(ctx);
 
@@ -1428,57 +1354,8 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
 	} for_each_vma_range(vmi, cur, end);
 	BUG_ON(!found);
 
-	vma_iter_set(&vmi, start);
-	prev = vma_prev(&vmi);
-	if (vma->vm_start < start)
-		prev = vma;
-
-	ret = 0;
-	for_each_vma_range(vmi, vma, end) {
-		cond_resched();
-
-		BUG_ON(!vma_can_userfault(vma, vm_flags, wp_async));
-		BUG_ON(vma->vm_userfaultfd_ctx.ctx &&
-		       vma->vm_userfaultfd_ctx.ctx != ctx);
-		WARN_ON(!(vma->vm_flags & VM_MAYWRITE));
-
-		/*
-		 * Nothing to do: this vma is already registered into this
-		 * userfaultfd and with the right tracking mode too.
-		 */
-		if (vma->vm_userfaultfd_ctx.ctx == ctx &&
-		    (vma->vm_flags & vm_flags) == vm_flags)
-			goto skip;
-
-		if (vma->vm_start > start)
-			start = vma->vm_start;
-		vma_end = min(end, vma->vm_end);
-
-		new_flags = (vma->vm_flags & ~__VM_UFFD_FLAGS) | vm_flags;
-		vma = vma_modify_flags_uffd(&vmi, prev, vma, start, vma_end,
-					    new_flags,
-					    (struct vm_userfaultfd_ctx){ctx});
-		if (IS_ERR(vma)) {
-			ret = PTR_ERR(vma);
-			break;
-		}
-
-		/*
-		 * In the vma_merge() successful mprotect-like case 8:
-		 * the next vma was merged into the current one and
-		 * the current one has not been updated yet.
-		 */
-		vma_start_write(vma);
-		userfaultfd_set_vm_flags(vma, new_flags);
-		vma->vm_userfaultfd_ctx.ctx = ctx;
-
-		if (is_vm_hugetlb_page(vma) && uffd_disable_huge_pmd_share(vma))
-			hugetlb_unshare_all_pmds(vma);
-
-	skip:
-		prev = vma;
-		start = vma->vm_end;
-	}
+	ret = userfaultfd_register_range(ctx, vma, vm_flags, start, end,
+					 wp_async);
 
 out_unlock:
 	mmap_write_unlock(mm);
@@ -1519,7 +1396,6 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 	struct vm_area_struct *vma, *prev, *cur;
 	int ret;
 	struct uffdio_range uffdio_unregister;
-	unsigned long new_flags;
 	bool found;
 	unsigned long start, end, vma_end;
 	const void __user *buf = (void __user *)arg;
@@ -1622,27 +1498,13 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx,
 			wake_userfault(vma->vm_userfaultfd_ctx.ctx, &range);
 		}
 
-		/* Reset ptes for the whole vma range if wr-protected */
-		if (userfaultfd_wp(vma))
-			uffd_wp_range(vma, start, vma_end - start, false);
-
-		new_flags = vma->vm_flags & ~__VM_UFFD_FLAGS;
-		vma = vma_modify_flags_uffd(&vmi, prev, vma, start, vma_end,
-					    new_flags, NULL_VM_UFFD_CTX);
+		vma = userfaultfd_clear_vma(&vmi, prev, vma,
+					    start, vma_end);
 		if (IS_ERR(vma)) {
 			ret = PTR_ERR(vma);
 			break;
 		}
 
-		/*
-		 * In the vma_merge() successful mprotect-like case 8:
-		 * the next vma was merged into the current one and
-		 * the current one has not been updated yet.
-		 */
-		vma_start_write(vma);
-		userfaultfd_set_vm_flags(vma, new_flags);
-		vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
-
 	skip:
 		prev = vma;
 		start = vma->vm_end;
include/linux/userfaultfd_k.h +19 -0
index 05d59f74fc88..6355ed5bd34b 100644
@@ -264,6 +264,25 @@ extern void userfaultfd_unmap_complete(struct mm_struct *mm,
 extern bool userfaultfd_wp_unpopulated(struct vm_area_struct *vma);
 extern bool userfaultfd_wp_async(struct vm_area_struct *vma);
 
+extern void userfaultfd_reset_ctx(struct vm_area_struct *vma);
+
+extern struct vm_area_struct *userfaultfd_clear_vma(struct vma_iterator *vmi,
+						    struct vm_area_struct *prev,
+						    struct vm_area_struct *vma,
+						    unsigned long start,
+						    unsigned long end);
+
+int userfaultfd_register_range(struct userfaultfd_ctx *ctx,
+			       struct vm_area_struct *vma,
+			       unsigned long vm_flags,
+			       unsigned long start, unsigned long end,
+			       bool wp_async);
+
+extern void userfaultfd_release_new(struct userfaultfd_ctx *ctx);
+
+extern void userfaultfd_release_all(struct mm_struct *mm,
+				    struct userfaultfd_ctx *ctx);
+
 #else /* CONFIG_USERFAULTFD */
 
 /* mm helpers */
mm/userfaultfd.c +168 -0

171 lines not on this page · raw message

Signature · 1 line
2.45.1
#2 lore raw

RFC PATCH v2 2/7 mm: move vma_modify() and helpers to internal header

In reply to Lorenzo Stoakes

These are core VMA manipulation functions which invoke VMA splitting and merging and should not be directly accessed from outside of mm/.

---
 include/linux/mm.h | 60 ---------------------------------------------
 mm/internal.h      | 61 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 60 deletions(-)
include/linux/mm.h +0 -60
index 5f1075d19600..4d2b5538925b 100644
@@ -3285,66 +3285,6 @@ extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
 	unsigned long addr, unsigned long len, pgoff_t pgoff,
 	bool *need_rmap_locks);
 extern void exit_mmap(struct mm_struct *);
-struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
-				  struct vm_area_struct *prev,
-				  struct vm_area_struct *vma,
-				  unsigned long start, unsigned long end,
-				  unsigned long vm_flags,
-				  struct mempolicy *policy,
-				  struct vm_userfaultfd_ctx uffd_ctx,
-				  struct anon_vma_name *anon_name);
-
-/* We are about to modify the VMA's flags. */
-static inline struct vm_area_struct
-*vma_modify_flags(struct vma_iterator *vmi,
-		  struct vm_area_struct *prev,
-		  struct vm_area_struct *vma,
-		  unsigned long start, unsigned long end,
-		  unsigned long new_flags)
-{
-	return vma_modify(vmi, prev, vma, start, end, new_flags,
-			  vma_policy(vma), vma->vm_userfaultfd_ctx,
-			  anon_vma_name(vma));
-}
-
-/* We are about to modify the VMA's flags and/or anon_name. */
-static inline struct vm_area_struct
-*vma_modify_flags_name(struct vma_iterator *vmi,
-		       struct vm_area_struct *prev,
-		       struct vm_area_struct *vma,
-		       unsigned long start,
-		       unsigned long end,
-		       unsigned long new_flags,
-		       struct anon_vma_name *new_name)
-{
-	return vma_modify(vmi, prev, vma, start, end, new_flags,
-			  vma_policy(vma), vma->vm_userfaultfd_ctx, new_name);
-}
-
-/* We are about to modify the VMA's memory policy. */
-static inline struct vm_area_struct
-*vma_modify_policy(struct vma_iterator *vmi,
-		   struct vm_area_struct *prev,
-		   struct vm_area_struct *vma,
-		   unsigned long start, unsigned long end,
-		   struct mempolicy *new_pol)
-{
-	return vma_modify(vmi, prev, vma, start, end, vma->vm_flags,
-			  new_pol, vma->vm_userfaultfd_ctx, anon_vma_name(vma));
-}
-
-/* We are about to modify the VMA's flags and/or uffd context. */
-static inline struct vm_area_struct
-*vma_modify_flags_uffd(struct vma_iterator *vmi,
-		       struct vm_area_struct *prev,
-		       struct vm_area_struct *vma,
-		       unsigned long start, unsigned long end,
-		       unsigned long new_flags,
-		       struct vm_userfaultfd_ctx new_ctx)
-{
-	return vma_modify(vmi, prev, vma, start, end, new_flags,
-			  vma_policy(vma), new_ctx, anon_vma_name(vma));
-}
 
 static inline int check_data_rlimit(unsigned long rlim,
 				    unsigned long new,
mm/internal.h +61 -0

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Signature · 1 line
2.45.1
#3 lore raw

RFC PATCH v2 3/7 mm: move vma_shrink(), vma_expand() to internal header

In reply to Lorenzo Stoakes

The vma_shrink() and vma_expand() functions are internal VMA manipulation functions which we ought to abstract for use outside of memory management code.

To achieve this, we abstract the operation performed in fs/exec.c by shift_arg_pages() into a new relocate_vma() function implemented in mm/mmap.c, which enables us to also move move_page_tables() and vma_iter_prev_range() to internal.h.

The purpose of doing this is to isolate key VMA manipulation functions in order that we can both abstract them and later render them easily testable.

---
 fs/exec.c          | 68 ++------------------------------------
 include/linux/mm.h | 17 +---------
 mm/internal.h      | 18 +++++++++++
 mm/mmap.c          | 81 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 102 insertions(+), 82 deletions(-)
fs/exec.c +2 -66
index 40073142288f..5cf53e20d8df 100644
@@ -683,75 +683,11 @@ static int copy_strings_kernel(int argc, const char *const *argv,
 /*
  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
  * the binfmt code determines where the new stack should reside, we shift it to
- * its final location.  The process proceeds as follows:
- *
- * 1) Use shift to calculate the new vma endpoints.
- * 2) Extend vma to cover both the old and new ranges.  This ensures the
- *    arguments passed to subsequent functions are consistent.
- * 3) Move vma's page tables to the new range.
- * 4) Free up any cleared pgd range.
- * 5) Shrink the vma to cover only the new range.
+ * its final location.
  */
 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 {
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long old_start = vma->vm_start;
-	unsigned long old_end = vma->vm_end;
-	unsigned long length = old_end - old_start;
-	unsigned long new_start = old_start - shift;
-	unsigned long new_end = old_end - shift;
-	VMA_ITERATOR(vmi, mm, new_start);
-	struct vm_area_struct *next;
-	struct mmu_gather tlb;
-
-	BUG_ON(new_start > new_end);
-
-	/*
-	 * ensure there are no vmas between where we want to go
-	 * and where we are
-	 */
-	if (vma != vma_next(&vmi))
-		return -EFAULT;
-
-	vma_iter_prev_range(&vmi);
-	/*
-	 * cover the whole range: [new_start, old_end)
-	 */
-	if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
-		return -ENOMEM;
-
-	/*
-	 * move the page tables downwards, on failure we rely on
-	 * process cleanup to remove whatever mess we made.
-	 */
-	if (length != move_page_tables(vma, old_start,
-				       vma, new_start, length, false, true))
-		return -ENOMEM;
-
-	lru_add_drain();
-	tlb_gather_mmu(&tlb, mm);
-	next = vma_next(&vmi);
-	if (new_end > old_start) {
-		/*
-		 * when the old and new regions overlap clear from new_end.
-		 */
-		free_pgd_range(&tlb, new_end, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	} else {
-		/*
-		 * otherwise, clean from old_start; this is done to not touch
-		 * the address space in [new_end, old_start) some architectures
-		 * have constraints on va-space that make this illegal (IA64) -
-		 * for the others its just a little faster.
-		 */
-		free_pgd_range(&tlb, old_start, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	}
-	tlb_finish_mmu(&tlb);
-
-	vma_prev(&vmi);
-	/* Shrink the vma to just the new range */
-	return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
+	return relocate_vma(vma, shift);
 }
 
 /*
include/linux/mm.h +1 -16
index 4d2b5538925b..ab4b70f2ce94 100644
@@ -998,12 +998,6 @@ static inline struct vm_area_struct *vma_prev(struct vma_iterator *vmi)
 	return mas_prev(&vmi->mas, 0);
 }
 
-static inline
-struct vm_area_struct *vma_iter_prev_range(struct vma_iterator *vmi)
-{
-	return mas_prev_range(&vmi->mas, 0);
-}
-
 static inline unsigned long vma_iter_addr(struct vma_iterator *vmi)
 {
 	return vmi->mas.index;
@@ -2523,11 +2517,6 @@ int set_page_dirty_lock(struct page *page);
 
 int get_cmdline(struct task_struct *task, char *buffer, int buflen);
 
-extern unsigned long move_page_tables(struct vm_area_struct *vma,
-		unsigned long old_addr, struct vm_area_struct *new_vma,
-		unsigned long new_addr, unsigned long len,
-		bool need_rmap_locks, bool for_stack);
-
 /*
  * Flags used by change_protection().  For now we make it a bitmap so
  * that we can pass in multiple flags just like parameters.  However
@@ -3273,11 +3262,6 @@ void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
 
 /* mmap.c */
 extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
-extern int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		      unsigned long start, unsigned long end, pgoff_t pgoff,
-		      struct vm_area_struct *next);
-extern int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		       unsigned long start, unsigned long end, pgoff_t pgoff);
 extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
 extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
 extern void unlink_file_vma(struct vm_area_struct *);
@@ -3285,6 +3269,7 @@ extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
 	unsigned long addr, unsigned long len, pgoff_t pgoff,
 	bool *need_rmap_locks);
 extern void exit_mmap(struct mm_struct *);
+extern int relocate_vma(struct vm_area_struct *vma, unsigned long shift);
 
 static inline int check_data_rlimit(unsigned long rlim,
 				    unsigned long new,
mm/internal.h +18 -0
index 164f03c6bce2..8c7aa5860df4 100644
@@ -1304,6 +1304,12 @@ static inline struct vm_area_struct
 			  vma_policy(vma), new_ctx, anon_vma_name(vma));
 }
 
+int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
+	      unsigned long start, unsigned long end, pgoff_t pgoff,
+	      struct vm_area_struct *next);
+int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
+	       unsigned long start, unsigned long end, pgoff_t pgoff);
+
 enum {
 	/* mark page accessed */
 	FOLL_TOUCH = 1 << 16,
@@ -1527,6 +1533,12 @@ static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
 	return 0;
 }
 
+static inline
+struct vm_area_struct *vma_iter_prev_range(struct vma_iterator *vmi)
+{
+	return mas_prev_range(&vmi->mas, 0);
+}
+
 /*
  * VMA lock generalization
  */
@@ -1638,4 +1650,10 @@ void unlink_file_vma_batch_init(struct unlink_vma_file_batch *);
 void unlink_file_vma_batch_add(struct unlink_vma_file_batch *, struct vm_area_struct *);
 void unlink_file_vma_batch_final(struct unlink_vma_file_batch *);
 
+/* mremap.c */
+unsigned long move_page_tables(struct vm_area_struct *vma,
+	unsigned long old_addr, struct vm_area_struct *new_vma,
+	unsigned long new_addr, unsigned long len,
+	bool need_rmap_locks, bool for_stack);
+
 #endif	/* __MM_INTERNAL_H */
mm/mmap.c +81 -0

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Signature · 1 line
2.45.1
#6 lore raw

RFC PATCH v2 4/7 mm: move internal core VMA manipulation functions to own file

In reply to Lorenzo Stoakes

This patch introduces vma.c and moves internal core VMA manipulation functions to this file from mmap.c.

This allows us to isolate VMA functionality in a single place such that we can create userspace testing code that invokes this functionality in an environment where we can implement simple unit tests of core functionality.

This patch ensures that core VMA functionality is explicitly marked as such by its presence in mm/vma.h.

It also places the header includes required by vma.c in vma_internal.h, which is simply imported by vma.c. This makes the VMA functionality testable, as userland testing code can simply stub out functionality as required.

---
 include/linux/mm.h |   35 -
 mm/Makefile        |    2 +-
 mm/internal.h      |  236 +-----
 mm/mmap.c          | 1981 +++-----------------------------------------
 mm/mmu_notifier.c  |    2 +
 mm/vma.c           | 1766 +++++++++++++++++++++++++++++++++++++++
 mm/vma.h           |  362 ++++++++
 mm/vma_internal.h  |   52 ++
 8 files changed, 2293 insertions(+), 2143 deletions(-)
 create mode 100644 mm/vma.c
 create mode 100644 mm/vma.h
 create mode 100644 mm/vma_internal.h
include/linux/mm.h +0 -35
index ab4b70f2ce94..3afcf6ae5854 100644
@@ -998,21 +998,6 @@ static inline struct vm_area_struct *vma_prev(struct vma_iterator *vmi)
 	return mas_prev(&vmi->mas, 0);
 }
 
-static inline unsigned long vma_iter_addr(struct vma_iterator *vmi)
-{
-	return vmi->mas.index;
-}
-
-static inline unsigned long vma_iter_end(struct vma_iterator *vmi)
-{
-	return vmi->mas.last + 1;
-}
-static inline int vma_iter_bulk_alloc(struct vma_iterator *vmi,
-				      unsigned long count)
-{
-	return mas_expected_entries(&vmi->mas, count);
-}
-
 static inline int vma_iter_clear_gfp(struct vma_iterator *vmi,
 			unsigned long start, unsigned long end, gfp_t gfp)
 {
@@ -2537,21 +2522,6 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen);
 #define  MM_CP_UFFD_WP_ALL                 (MM_CP_UFFD_WP | \
 					    MM_CP_UFFD_WP_RESOLVE)
 
-bool vma_needs_dirty_tracking(struct vm_area_struct *vma);
-bool vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot);
-static inline bool vma_wants_manual_pte_write_upgrade(struct vm_area_struct *vma)
-{
-	/*
-	 * We want to check manually if we can change individual PTEs writable
-	 * if we can't do that automatically for all PTEs in a mapping. For
-	 * private mappings, that's always the case when we have write
-	 * permissions as we properly have to handle COW.
-	 */
-	if (vma->vm_flags & VM_SHARED)
-		return vma_wants_writenotify(vma, vma->vm_page_prot);
-	return !!(vma->vm_flags & VM_WRITE);
-
-}
 bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
 			     pte_t pte);
 extern long change_protection(struct mmu_gather *tlb,
@@ -3262,12 +3232,7 @@ void anon_vma_interval_tree_verify(struct anon_vma_chain *node);
 
 /* mmap.c */
 extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin);
-extern struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *);
 extern int insert_vm_struct(struct mm_struct *, struct vm_area_struct *);
-extern void unlink_file_vma(struct vm_area_struct *);
-extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
-	unsigned long addr, unsigned long len, pgoff_t pgoff,
-	bool *need_rmap_locks);
 extern void exit_mmap(struct mm_struct *);
 extern int relocate_vma(struct vm_area_struct *vma, unsigned long shift);
 
mm/Makefile +1 -1
index d2915f8c9dc0..140a22654dde 100644
@@ -37,7 +37,7 @@ mmu-y			:= nommu.o
 mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
 			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
 			   msync.o page_vma_mapped.o pagewalk.o \
-			   pgtable-generic.o rmap.o vmalloc.o
+			   pgtable-generic.o rmap.o vmalloc.o vma.o
 
 
 ifdef CONFIG_CROSS_MEMORY_ATTACH
mm/internal.h +5 -231

273 lines not on this page · raw message

mm/mmap.c +105 -1876

2,064 lines not on this page · raw message

mm/mmu_notifier.c +2 -0
index 8982e6139d07..fc18fe274505 100644
@@ -19,6 +19,8 @@
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
 
+#include "vma.h"
+
 /* global SRCU for all MMs */
 DEFINE_STATIC_SRCU(srcu);
 
mm/vma.c new file +1766 -0

593 lines not on this page · raw message

mm/vma.h new file +362 -0

362 lines not on this page · raw message

mm/vma_internal.h new file +52 -0

52 lines not on this page · raw message

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#9 lore raw

RFC PATCH v2 5/7 MAINTAINERS: Add entry for new VMA files

In reply to Lorenzo Stoakes

The vma files contain logic split from mmap.c for the most part and are all relevant to VMA logic, so maintain the same reviewers for both.

---
 MAINTAINERS | 13 +++++++++++++
 1 file changed, 13 insertions(+)
MAINTAINERS +13 -0
index 098d214f78d9..0847cb5903ab 100644
@@ -23971,6 +23971,19 @@ F:	include/uapi/linux/vsockmon.h
 F:	net/vmw_vsock/
 F:	tools/testing/vsock/
 
+VMA
+M:	Andrew Morton <[email protected]>
+R:	Liam R. Howlett <[email protected]>
+R:	Vlastimil Babka <[email protected]>
+R:	Lorenzo Stoakes <[email protected]>
+L:	[email protected]
+S:	Maintained
+W:	http://www.linux-mm.org
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
+F:	mm/vma.c
+F:	mm/vma.h
+F:	mm/vma_internal.h
+
 VMALLOC
 M:	Andrew Morton <[email protected]>
 R:	Uladzislau Rezki <[email protected]>
Signature · 1 line
2.45.1
#12 lore raw

RFC PATCH v2 6/7 tools: separate out shared radix-tree components

In reply to Lorenzo Stoakes

The core components contained within the radix-tree tests which provide shims for kernel headers and access to the maple tree are useful for testing other things, so separate them out and make the radix tree tests dependent on the shared components.

This lays the groundwork for us to add VMA tests of the newly introduced vma.c file.

---
 tools/testing/radix-tree/Makefile             | 68 +++----------------
 tools/testing/radix-tree/maple.c              | 14 +---
 tools/testing/radix-tree/xarray.c             |  9 +--
 tools/testing/shared/autoconf.h               |  2 +
 tools/testing/{radix-tree => shared}/bitmap.c |  0
 tools/testing/{radix-tree => shared}/linux.c  |  0
 .../{radix-tree => shared}/linux/bug.h        |  0
 .../{radix-tree => shared}/linux/cpu.h        |  0
 .../{radix-tree => shared}/linux/idr.h        |  0
 .../{radix-tree => shared}/linux/init.h       |  0
 .../{radix-tree => shared}/linux/kconfig.h    |  0
 .../{radix-tree => shared}/linux/kernel.h     |  0
 .../{radix-tree => shared}/linux/kmemleak.h   |  0
 .../{radix-tree => shared}/linux/local_lock.h |  0
 .../{radix-tree => shared}/linux/lockdep.h    |  0
 .../{radix-tree => shared}/linux/maple_tree.h |  0
 .../{radix-tree => shared}/linux/percpu.h     |  0
 .../{radix-tree => shared}/linux/preempt.h    |  0
 .../{radix-tree => shared}/linux/radix-tree.h |  0
 .../{radix-tree => shared}/linux/rcupdate.h   |  0
 .../{radix-tree => shared}/linux/xarray.h     |  0
 tools/testing/shared/maple-shared.h           |  9 +++
 tools/testing/shared/maple-shim.c             |  7 ++
 tools/testing/shared/shared.h                 | 34 ++++++++++
 tools/testing/shared/shared.mk                | 68 +++++++++++++++++++
 .../testing/shared/trace/events/maple_tree.h  |  5 ++
 tools/testing/shared/xarray-shared.c          |  5 ++
 tools/testing/shared/xarray-shared.h          |  4 ++
 28 files changed, 147 insertions(+), 78 deletions(-)
 create mode 100644 tools/testing/shared/autoconf.h
 rename tools/testing/{radix-tree => shared}/bitmap.c (100%)
 rename tools/testing/{radix-tree => shared}/linux.c (100%)
 rename tools/testing/{radix-tree => shared}/linux/bug.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/cpu.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/idr.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/init.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kconfig.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kernel.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kmemleak.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/local_lock.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/lockdep.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/maple_tree.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/percpu.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/preempt.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/radix-tree.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/rcupdate.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/xarray.h (100%)
 create mode 100644 tools/testing/shared/maple-shared.h
 create mode 100644 tools/testing/shared/maple-shim.c
 create mode 100644 tools/testing/shared/shared.h
 create mode 100644 tools/testing/shared/shared.mk
 create mode 100644 tools/testing/shared/trace/events/maple_tree.h
 create mode 100644 tools/testing/shared/xarray-shared.c
 create mode 100644 tools/testing/shared/xarray-shared.h
tools/testing/radix-tree/Makefile +11 -57
index 7527f738b4a1..29d607063749 100644
@@ -1,29 +1,16 @@
 # SPDX-License-Identifier: GPL-2.0
 
-CFLAGS += -I. -I../../include -I../../../lib -g -Og -Wall \
-	  -D_LGPL_SOURCE -fsanitize=address -fsanitize=undefined
-LDFLAGS += -fsanitize=address -fsanitize=undefined
-LDLIBS+= -lpthread -lurcu
-TARGETS = main idr-test multiorder xarray maple
-CORE_OFILES := xarray.o radix-tree.o idr.o linux.o test.o find_bit.o bitmap.o \
-			 slab.o maple.o
-OFILES = main.o $(CORE_OFILES) regression1.o regression2.o regression3.o \
-	 regression4.o tag_check.o multiorder.o idr-test.o iteration_check.o \
-	 iteration_check_2.o benchmark.o
+.PHONY: default
 
-ifndef SHIFT
-	SHIFT=3
-endif
+default: main
 
-ifeq ($(BUILD), 32)
-	CFLAGS += -m32
-	LDFLAGS += -m32
-LONG_BIT := 32
-endif
+include ../shared/shared.mk
 
-ifndef LONG_BIT
-LONG_BIT := $(shell getconf LONG_BIT)
-endif
+TARGETS = main idr-test multiorder xarray maple
+CORE_OFILES = $(SHARED_OFILES) xarray.o maple.o test.o
+OFILES = main.o $(CORE_OFILES) regression1.o regression2.o \
+	 regression3.o regression4.o tag_check.o multiorder.o idr-test.o \
+	iteration_check.o iteration_check_2.o benchmark.o
 
 targets: generated/map-shift.h generated/bit-length.h $(TARGETS)
 
@@ -32,46 +19,13 @@ main:	$(OFILES)
 idr-test.o: ../../../lib/test_ida.c
 idr-test: idr-test.o $(CORE_OFILES)
 
-xarray: $(CORE_OFILES)
+xarray: $(CORE_OFILES) xarray.o
 
-maple: $(CORE_OFILES)
+maple: $(CORE_OFILES) maple.o
 
 multiorder: multiorder.o $(CORE_OFILES)
 
 clean:
 	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/map-shift.h generated/bit-length.h
 
-vpath %.c ../../lib
-
-$(OFILES): Makefile *.h */*.h generated/map-shift.h generated/bit-length.h \
-	../../include/linux/*.h \
-	../../include/asm/*.h \
-	../../../include/linux/xarray.h \
-	../../../include/linux/maple_tree.h \
-	../../../include/linux/radix-tree.h \
-	../../../lib/radix-tree.h \
-	../../../include/linux/idr.h
-
-radix-tree.c: ../../../lib/radix-tree.c
-	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
-
-idr.c: ../../../lib/idr.c
-	sed -e 's/^static //' -e 's/__always_inline //' -e 's/inline //' < $< > $@
-
-xarray.o: ../../../lib/xarray.c ../../../lib/test_xarray.c
-
-maple.o: ../../../lib/maple_tree.c ../../../lib/test_maple_tree.c
-
-generated/map-shift.h:
-	@if ! grep -qws $(SHIFT) generated/map-shift.h; then		\
-		echo "#define XA_CHUNK_SHIFT $(SHIFT)" >		\
-				generated/map-shift.h;			\
-	fi
-
-generated/bit-length.h: FORCE
-	@if ! grep -qws CONFIG_$(LONG_BIT)BIT generated/bit-length.h; then   \
-		echo "Generating $@";                                        \
-		echo "#define CONFIG_$(LONG_BIT)BIT 1" > $@;                 \
-	fi
-
-FORCE: ;
+$(OFILES): $(SHARED_DEPS) *.h */*.h
tools/testing/radix-tree/maple.c +1 -13
index f1caf4bcf937..5b53ecf22fc4 100644
@@ -8,20 +8,8 @@
  * difficult to handle in kernel tests.
  */
 
-#define CONFIG_DEBUG_MAPLE_TREE
-#define CONFIG_MAPLE_SEARCH
-#define MAPLE_32BIT (MAPLE_NODE_SLOTS > 31)
+#include "maple-shared.h"
 #include "test.h"
-#include <stdlib.h>
-#include <time.h>
-#include "linux/init.h"
-
-#define module_init(x)
-#define module_exit(x)
-#define MODULE_AUTHOR(x)
-#define MODULE_LICENSE(x)
-#define dump_stack()	assert(0)
-
 #include "../../../lib/maple_tree.c"
 #include "../../../lib/test_maple_tree.c"
 
tools/testing/radix-tree/xarray.c +1 -8
index f20e12cbbfd4..253208a8541b 100644
@@ -4,16 +4,9 @@
  * Copyright (c) 2018 Matthew Wilcox <[email protected]>
  */
 
-#define XA_DEBUG
+#include "xarray-shared.h"
 #include "test.h"
 
-#define module_init(x)
-#define module_exit(x)
-#define MODULE_AUTHOR(x)
-#define MODULE_LICENSE(x)
-#define dump_stack()	assert(0)
-
-#include "../../../lib/xarray.c"
 #undef XA_DEBUG
 #include "../../../lib/test_xarray.c"
 
tools/testing/shared/autoconf.h new file +2 -0
new file mode 100644
index 000000000000..92dc474c349b
@@ -0,0 +1,2 @@
+#include "bit-length.h"
+#define CONFIG_XARRAY_MULTI 1
tools/testing/shared/bitmap.c renamed from tools/testing/radix-tree/bitmap.c +0 -0
similarity index 100%
rename from tools/testing/radix-tree/bitmap.c
rename to tools/testing/shared/bitmap.c
tools/testing/shared/linux.c renamed from tools/testing/radix-tree/linux.c +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux.c
rename to tools/testing/shared/linux.c
tools/testing/shared/linux/bug.h renamed from tools/testing/radix-tree/linux/bug.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/bug.h
rename to tools/testing/shared/linux/bug.h
tools/testing/shared/linux/cpu.h renamed from tools/testing/radix-tree/linux/cpu.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/cpu.h
rename to tools/testing/shared/linux/cpu.h
tools/testing/shared/linux/idr.h renamed from tools/testing/radix-tree/linux/idr.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/idr.h
rename to tools/testing/shared/linux/idr.h
tools/testing/shared/linux/init.h renamed from tools/testing/radix-tree/linux/init.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/init.h
rename to tools/testing/shared/linux/init.h
tools/testing/shared/linux/kconfig.h renamed from tools/testing/radix-tree/linux/kconfig.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/kconfig.h
rename to tools/testing/shared/linux/kconfig.h
tools/testing/shared/linux/kernel.h renamed from tools/testing/radix-tree/linux/kernel.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/kernel.h
rename to tools/testing/shared/linux/kernel.h
tools/testing/shared/linux/kmemleak.h renamed from tools/testing/radix-tree/linux/kmemleak.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/kmemleak.h
rename to tools/testing/shared/linux/kmemleak.h
tools/testing/shared/linux/local_lock.h renamed from tools/testing/radix-tree/linux/local_lock.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/local_lock.h
rename to tools/testing/shared/linux/local_lock.h
tools/testing/shared/linux/lockdep.h renamed from tools/testing/radix-tree/linux/lockdep.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/lockdep.h
rename to tools/testing/shared/linux/lockdep.h
tools/testing/shared/linux/maple_tree.h renamed from tools/testing/radix-tree/linux/maple_tree.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/maple_tree.h
rename to tools/testing/shared/linux/maple_tree.h
tools/testing/shared/linux/percpu.h renamed from tools/testing/radix-tree/linux/percpu.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/percpu.h
rename to tools/testing/shared/linux/percpu.h
tools/testing/shared/linux/preempt.h renamed from tools/testing/radix-tree/linux/preempt.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/preempt.h
rename to tools/testing/shared/linux/preempt.h
tools/testing/shared/linux/radix-tree.h renamed from tools/testing/radix-tree/linux/radix-tree.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/radix-tree.h
rename to tools/testing/shared/linux/radix-tree.h
tools/testing/shared/linux/rcupdate.h renamed from tools/testing/radix-tree/linux/rcupdate.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/rcupdate.h
rename to tools/testing/shared/linux/rcupdate.h
tools/testing/shared/linux/xarray.h renamed from tools/testing/radix-tree/linux/xarray.h +0 -0
similarity index 100%
rename from tools/testing/radix-tree/linux/xarray.h
rename to tools/testing/shared/linux/xarray.h
tools/testing/shared/maple-shared.h new file +9 -0
new file mode 100644
index 000000000000..3d847edd149d
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#define CONFIG_DEBUG_MAPLE_TREE
+#define CONFIG_MAPLE_SEARCH
+#define MAPLE_32BIT (MAPLE_NODE_SLOTS > 31)
+#include "shared.h"
+#include <stdlib.h>
+#include <time.h>
+#include "linux/init.h"
tools/testing/shared/maple-shim.c new file +7 -0
new file mode 100644
index 000000000000..640df76f483e
@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+/* Very simple shim around the maple tree. */
+
+#include "maple-shared.h"
+
+#include "../../../lib/maple_tree.c"
tools/testing/shared/shared.h new file +34 -0
new file mode 100644
index 000000000000..495602e60b65
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/types.h>
+#include <linux/bug.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+
+#include <linux/gfp.h>
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+
+#ifndef module_init
+#define module_init(x)
+#endif
+
+#ifndef module_exit
+#define module_exit(x)
+#endif
+
+#ifndef MODULE_AUTHOR
+#define MODULE_AUTHOR(x)
+#endif
+
+#ifndef MODULE_LICENSE
+#define MODULE_LICENSE(x)
+#endif
+
+#ifndef MODULE_DESCRIPTION
+#define MODULE_DESCRIPTION(x)
+#endif
+
+#ifndef dump_stack
+#define dump_stack()	assert(0)
+#endif
tools/testing/shared/shared.mk new file +68 -0

68 lines not on this page · raw message

tools/testing/shared/trace/events/maple_tree.h new file +5 -0
new file mode 100644
index 000000000000..97d0e1ddcf08
@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#define trace_ma_op(a, b) do {} while (0)
+#define trace_ma_read(a, b) do {} while (0)
+#define trace_ma_write(a, b, c, d) do {} while (0)
tools/testing/shared/xarray-shared.c new file +5 -0
new file mode 100644
index 000000000000..e90901958dcd
@@ -0,0 +1,5 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "xarray-shared.h"
+
+#include "../../../lib/xarray.c"
tools/testing/shared/xarray-shared.h new file +4 -0
new file mode 100644
index 000000000000..ac2d16ff53ae
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#define XA_DEBUG
+#include "shared.h"
Signature · 1 line
2.45.1
#13 lore raw

RFC PATCH v2 7/7 tools: add skeleton code for userland testing of VMA logic

In reply to Lorenzo Stoakes

Establish a new userland VMA unit testing implementation under tools/testing which utilises existing logic providing maple tree support in userland utilising the now-shared code previously exclusive to radix tree testing.

This provides fundamental VMA operations whose API is defined in mm/vma.h, while stubbing out superfluous functionality.

This exists as a proof-of-concept, with the test implementation functional and sufficient to allow userland compilation of vma.c, but containing only cursory tests to demonstrate basic functionality.

---
 MAINTAINERS                            |   1 +
 include/linux/atomic.h                 |   2 +-
 include/linux/mmzone.h                 |   3 +-
 tools/testing/vma/.gitignore           |   6 +
 tools/testing/vma/Makefile             |  15 +
 tools/testing/vma/errors.txt           |   0
 tools/testing/vma/generated/autoconf.h |   2 +
 tools/testing/vma/linux/atomic.h       |  12 +
 tools/testing/vma/linux/mmzone.h       |  38 ++
 tools/testing/vma/vma.c                | 207 ++++++
 tools/testing/vma/vma_internal.h       | 882 +++++++++++++++++++++++++
 11 files changed, 1166 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/vma/.gitignore
 create mode 100644 tools/testing/vma/Makefile
 create mode 100644 tools/testing/vma/errors.txt
 create mode 100644 tools/testing/vma/generated/autoconf.h
 create mode 100644 tools/testing/vma/linux/atomic.h
 create mode 100644 tools/testing/vma/linux/mmzone.h
 create mode 100644 tools/testing/vma/vma.c
 create mode 100644 tools/testing/vma/vma_internal.h
MAINTAINERS +1 -0
index 0847cb5903ab..410062bd8e21 100644
@@ -23983,6 +23983,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
 F:	mm/vma.c
 F:	mm/vma.h
 F:	mm/vma_internal.h
+F:	tools/testing/vma
 
 VMALLOC
 M:	Andrew Morton <[email protected]>
include/linux/atomic.h +1 -1
index 8dd57c3a99e9..badfba2fd10f 100644
@@ -81,4 +81,4 @@
 #include <linux/atomic/atomic-long.h>
 #include <linux/atomic/atomic-instrumented.h>
 
-#endif /* _LINUX_ATOMIC_H */
+#endif	/* _LINUX_ATOMIC_H */
include/linux/mmzone.h +2 -1
index 41458892bc8a..30a22e57fa50 100644
@@ -1,4 +1,5 @@
-/* SPDX-License-Identifier: GPL-2.0 */
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
 #ifndef _LINUX_MMZONE_H
 #define _LINUX_MMZONE_H
 
tools/testing/vma/.gitignore new file +6 -0
new file mode 100644
index 000000000000..d915f7d7fb1a
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0-only
+generated/bit-length.h
+generated/map-shift.h
+idr.c
+radix-tree.c
+vma
tools/testing/vma/Makefile new file +15 -0
new file mode 100644
index 000000000000..a12fb6596016
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+
+.PHONY: default
+
+default: vma
+
+include ../shared/shared.mk
+
+OFILES = vma.o $(SHARED_OFILES) maple-shim.o
+TARGETS = vma
+
+vma:	$(OFILES)
+
+clean:
+	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/map-shift.h generated/bit-length.h
tools/testing/vma/errors.txt new file +0 -0
new file mode 100644
index 000000000000..e69de29bb2d1
tools/testing/vma/generated/autoconf.h new file +2 -0
new file mode 100644
index 000000000000..92dc474c349b
@@ -0,0 +1,2 @@
+#include "bit-length.h"
+#define CONFIG_XARRAY_MULTI 1
tools/testing/vma/linux/atomic.h new file +12 -0
new file mode 100644
index 000000000000..e01f66f98982
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _LINUX_ATOMIC_H
+#define _LINUX_ATOMIC_H
+
+#define atomic_t int32_t
+#define atomic_inc(x) uatomic_inc(x)
+#define atomic_read(x) uatomic_read(x)
+#define atomic_set(x, y) do {} while (0)
+#define U8_MAX UCHAR_MAX
+
+#endif	/* _LINUX_ATOMIC_H */
tools/testing/vma/linux/mmzone.h new file +38 -0
new file mode 100644
index 000000000000..e6a96c686610
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _LINUX_MMZONE_H
+#define _LINUX_MMZONE_H
+
+#include <linux/atomic.h>
+
+struct pglist_data *first_online_pgdat(void);
+struct pglist_data *next_online_pgdat(struct pglist_data *pgdat);
+
+#define for_each_online_pgdat(pgdat)			\
+	for (pgdat = first_online_pgdat();		\
+	     pgdat;					\
+	     pgdat = next_online_pgdat(pgdat))
+
+enum zone_type {
+	__MAX_NR_ZONES
+};
+
+#define MAX_NR_ZONES __MAX_NR_ZONES
+#define MAX_PAGE_ORDER 10
+#define MAX_ORDER_NR_PAGES (1 << MAX_PAGE_ORDER)
+
+#define pageblock_order		MAX_PAGE_ORDER
+#define pageblock_nr_pages	BIT(pageblock_order)
+#define pageblock_align(pfn)	ALIGN((pfn), pageblock_nr_pages)
+#define pageblock_start_pfn(pfn)	ALIGN_DOWN((pfn), pageblock_nr_pages)
+
+struct zone {
+	atomic_long_t		managed_pages;
+};
+
+typedef struct pglist_data {
+	struct zone node_zones[MAX_NR_ZONES];
+
+} pg_data_t;
+
+#endif /* _LINUX_MMZONE_H */
tools/testing/vma/vma.c new file +207 -0

207 lines not on this page · raw message

tools/testing/vma/vma_internal.h new file +882 -0

882 lines not on this page · raw message

Signature · 1 line
2.45.1
#4 lore raw

Re: [RFC PATCH v2 3/7] mm: move vma_shrink(), vma_expand() to internal header

In reply to Lorenzo Stoakes
Quoted 90 lines · Lorenzo Stoakes

The vma_shrink() and vma_expand() functions are internal VMA manipulation functions which we ought to abstract for use outside of memory management code.

To achieve this, we abstract the operation performed in fs/exec.c by shift_arg_pages() into a new relocate_vma() function implemented in mm/mmap.c, which enables us to also move move_page_tables() and vma_iter_prev_range() to internal.h.

The purpose of doing this is to isolate key VMA manipulation functions in order that we can both abstract them and later render them easily testable.

---
 fs/exec.c          | 68 ++------------------------------------
 include/linux/mm.h | 17 +---------
 mm/internal.h      | 18 +++++++++++
 mm/mmap.c          | 81 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 102 insertions(+), 82 deletions(-)
fs/exec.c +1 -58
index 40073142288f..5cf53e20d8df 100644
@@ -683,75 +683,11 @@ static int copy_strings_kernel(int argc, const char *const *argv,
 /*
  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
  * the binfmt code determines where the new stack should reside, we shift it to
- * its final location.  The process proceeds as follows:
- *
- * 1) Use shift to calculate the new vma endpoints.
- * 2) Extend vma to cover both the old and new ranges.  This ensures the
- *    arguments passed to subsequent functions are consistent.
- * 3) Move vma's page tables to the new range.
- * 4) Free up any cleared pgd range.
- * 5) Shrink the vma to cover only the new range.
+ * its final location.
  */
 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 {
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long old_start = vma->vm_start;
-	unsigned long old_end = vma->vm_end;
-	unsigned long length = old_end - old_start;
-	unsigned long new_start = old_start - shift;
-	unsigned long new_end = old_end - shift;
-	VMA_ITERATOR(vmi, mm, new_start);
-	struct vm_area_struct *next;
-	struct mmu_gather tlb;
-
-	BUG_ON(new_start > new_end);
-
-	/*
-	 * ensure there are no vmas between where we want to go
-	 * and where we are
-	 */
-	if (vma != vma_next(&vmi))
-		return -EFAULT;
-
-	vma_iter_prev_range(&vmi);
-	/*
-	 * cover the whole range: [new_start, old_end)
-	 */
-	if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
-		return -ENOMEM;
-
-	/*
-	 * move the page tables downwards, on failure we rely on
-	 * process cleanup to remove whatever mess we made.
-	 */
-	if (length != move_page_tables(vma, old_start,
-				       vma, new_start, length, false, true))
-		return -ENOMEM;
-
-	lru_add_drain();
-	tlb_gather_mmu(&tlb, mm);
-	next = vma_next(&vmi);
-	if (new_end > old_start) {
-		/*
-		 * when the old and new regions overlap clear from new_end.
-		 */
-		free_pgd_range(&tlb, new_end, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	} else {
-		/*
-		 * otherwise, clean from old_start; this is done to not touch
-		 * the address space in [new_end, old_start) some architectures
-		 * have constraints on va-space that make this illegal (IA64) -
-		 * for the others its just a little faster.
-		 */

fs/exec.c static int copy_strings_kernel(int argc, const char *const *argv, · line 691

Quoted 10 lines
fs/exec.c +1 -8
-		free_pgd_range(&tlb, old_start, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	}
-	tlb_finish_mmu(&tlb);
-
-	vma_prev(&vmi);
-	/* Shrink the vma to just the new range */
-	return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
+	return relocate_vma(vma, shift);
 }

The end result is a function that simply returns the results of your new function. shift_arg_pages() is used once and mentioned in a single comment in mm/mremap.c. I wonder if it's worth just dropping the function entirely and just replacing the call to shift_arg_pages() to relocate_vma()?

I'm happy either way, the compiler should do the Right Thing(tm) the way it is written.

...

fs/exec.c static int copy_strings_kernel(int argc, const char *const *argv,

Quoted 10 lines
fs/exec.c +10 -0
+
+/*
+ * Relocate a VMA downwards by shift bytes. There cannot be any VMAs between
+ * this VMA and its relocated range, which will now reside at [vma->vm_start -
+ * shift, vma->vm_end - shift).
+ *
+ * This function is almost certainly NOT what you want for anything other than
+ * early executable temporary stack relocation.
+ */
+int relocate_vma(struct vm_area_struct *vma, unsigned long shift)

The name relocate_vma() implies it could be used in any direction, but it can only shift downwards. This is also true for the shift_arg_pages() as well and at least the comments state which way things are going, and that the vma is also moving.

It might be worth stating the pages are also being relocated in the comment.

Again, I'm happy enough to keep it this way but I wanted to point it out.

...

Thanks,
Liam

#7 lore raw

Re: [RFC PATCH v2 4/7] mm: move internal core VMA manipulation functions to own file

In reply to Lorenzo Stoakes
Quoted 30 lines · Lorenzo Stoakes

This patch introduces vma.c and moves internal core VMA manipulation functions to this file from mmap.c.

This allows us to isolate VMA functionality in a single place such that we can create userspace testing code that invokes this functionality in an environment where we can implement simple unit tests of core functionality.

This patch ensures that core VMA functionality is explicitly marked as such by its presence in mm/vma.h.

It also places the header includes required by vma.c in vma_internal.h, which is simply imported by vma.c. This makes the VMA functionality testable, as userland testing code can simply stub out functionality as required.

---
 include/linux/mm.h |   35 -
 mm/Makefile        |    2 +-
 mm/internal.h      |  236 +-----
 mm/mmap.c          | 1981 +++-----------------------------------------
 mm/mmu_notifier.c  |    2 +
 mm/vma.c           | 1766 +++++++++++++++++++++++++++++++++++++++
 mm/vma.h           |  362 ++++++++
 mm/vma_internal.h  |   52 ++
 8 files changed, 2293 insertions(+), 2143 deletions(-)
 create mode 100644 mm/vma.c
 create mode 100644 mm/vma.h
 create mode 100644 mm/vma_internal.h

...

mm/mmap.c line 60

Quoted 9 lines
mm/mmap.c +1 -0
index d2eebbed87b9..721870f380bf 100644
@@ -57,6 +57,7 @@
 #include <trace/events/mmap.h>
 
 #include "internal.h"
+#include "vma.h"

This isn't needed as internal.h includes vma.h in this revision.

mm/mmap.c line 63

Quoted 3 lines
mm/mmap.c +0 -0
 #ifndef arch_mmap_check
 #define arch_mmap_check(addr, len, flags)	(0)

...

Thanks,
Liam

#10 lore raw

Re: [RFC PATCH v2 5/7] MAINTAINERS: Add entry for new VMA files

In reply to Lorenzo Stoakes

Hi Lorenzo,

Quoted 14 lines · On Fri, 28 Jun 2024 15:35:26 +0100 Lorenzo Stoakes <[email protected]> wrote:

The vma files contain logic split from mmap.c for the most part and are all relevant to VMA logic, so maintain the same reviewers for both.

---
 MAINTAINERS | 13 +++++++++++++
 1 file changed, 13 insertions(+)
MAINTAINERS +0 -0
index 098d214f78d9..0847cb5903ab 100644
@@ -23971,6 +23971,19 @@ F:	include/uapi/linux/vsockmon.h
 F:	net/vmw_vsock/

MAINTAINERS F: include/uapi/linux/vsockmon.h · line 23981

Quoted 10 lines
MAINTAINERS +8 -0
 F:	tools/testing/vsock/
 
+VMA
+M:	Andrew Morton <[email protected]>
+R:	Liam R. Howlett <[email protected]>
+R:	Vlastimil Babka <[email protected]>
+R:	Lorenzo Stoakes <[email protected]>
+L:	[email protected]
+S:	Maintained
+W:	http://www.linux-mm.org

I know this is just copy-pasted. But, what about using https instead of http?

Quoted 12 lines
MAINTAINERS +5 -0
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
+F:	mm/vma.c
+F:	mm/vma.h
+F:	mm/vma_internal.h
+
 VMALLOC
 M:	Andrew Morton <[email protected]>
 R:	Uladzislau Rezki <[email protected]>
Signature · 1 line
2.45.1

Thanks,
SJ

#14 lore raw

Re: [RFC PATCH v2 7/7] tools: add skeleton code for userland testing of VMA logic

In reply to Lorenzo Stoakes

Hi Lorenzo,

Quoted 40 lines · On Fri, 28 Jun 2024 15:35:28 +0100 Lorenzo Stoakes <[email protected]> wrote:

Establish a new userland VMA unit testing implementation under tools/testing which utilises existing logic providing maple tree support in userland utilising the now-shared code previously exclusive to radix tree testing.

This provides fundamental VMA operations whose API is defined in mm/vma.h, while stubbing out superfluous functionality.

This exists as a proof-of-concept, with the test implementation functional and sufficient to allow userland compilation of vma.c, but containing only cursory tests to demonstrate basic functionality.

---
 MAINTAINERS                            |   1 +
 include/linux/atomic.h                 |   2 +-
 include/linux/mmzone.h                 |   3 +-
 tools/testing/vma/.gitignore           |   6 +
 tools/testing/vma/Makefile             |  15 +
 tools/testing/vma/errors.txt           |   0
 tools/testing/vma/generated/autoconf.h |   2 +
 tools/testing/vma/linux/atomic.h       |  12 +
 tools/testing/vma/linux/mmzone.h       |  38 ++
 tools/testing/vma/vma.c                | 207 ++++++
 tools/testing/vma/vma_internal.h       | 882 +++++++++++++++++++++++++
 11 files changed, 1166 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/vma/.gitignore
 create mode 100644 tools/testing/vma/Makefile
 create mode 100644 tools/testing/vma/errors.txt
 create mode 100644 tools/testing/vma/generated/autoconf.h
 create mode 100644 tools/testing/vma/linux/atomic.h
 create mode 100644 tools/testing/vma/linux/mmzone.h
 create mode 100644 tools/testing/vma/vma.c
 create mode 100644 tools/testing/vma/vma_internal.h
MAINTAINERS +0 -0
index 0847cb5903ab..410062bd8e21 100644

MAINTAINERS T: git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm · line 23986

Quoted 4 lines
MAINTAINERS +1 -0
@@ -23983,6 +23983,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
 F:	mm/vma.c
 F:	mm/vma.h
 F:	mm/vma_internal.h
+F:	tools/testing/vma

According to the description of 'F:' section description at the beginning of this file (quoting below), I think adding a trailing slash to the above line would be nice?

F: *Files* and directories wildcard patterns.
A trailing slash includes all files and subdirectory files.
F: drivers/net/ all files in and below drivers/net

Thanks,
SJ

[...]

#5 lore raw

Re: [RFC PATCH v2 3/7] mm: move vma_shrink(), vma_expand() to internal header

In reply to Liam R. Howlett
Quoted 99 lines · Liam R. Howlett
Quoted 98 lines · Lorenzo Stoakes

The vma_shrink() and vma_expand() functions are internal VMA manipulation functions which we ought to abstract for use outside of memory management code.

To achieve this, we abstract the operation performed in fs/exec.c by shift_arg_pages() into a new relocate_vma() function implemented in mm/mmap.c, which enables us to also move move_page_tables() and vma_iter_prev_range() to internal.h.

The purpose of doing this is to isolate key VMA manipulation functions in order that we can both abstract them and later render them easily testable.

---
 fs/exec.c          | 68 ++------------------------------------
 include/linux/mm.h | 17 +---------
 mm/internal.h      | 18 +++++++++++
 mm/mmap.c          | 81 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 102 insertions(+), 82 deletions(-)
fs/exec.c +1 -66
index 40073142288f..5cf53e20d8df 100644
@@ -683,75 +683,11 @@ static int copy_strings_kernel(int argc, const char *const *argv,
 /*
  * During bprm_mm_init(), we create a temporary stack at STACK_TOP_MAX.  Once
  * the binfmt code determines where the new stack should reside, we shift it to
- * its final location.  The process proceeds as follows:
- *
- * 1) Use shift to calculate the new vma endpoints.
- * 2) Extend vma to cover both the old and new ranges.  This ensures the
- *    arguments passed to subsequent functions are consistent.
- * 3) Move vma's page tables to the new range.
- * 4) Free up any cleared pgd range.
- * 5) Shrink the vma to cover only the new range.
+ * its final location.
  */
 static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 {
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long old_start = vma->vm_start;
-	unsigned long old_end = vma->vm_end;
-	unsigned long length = old_end - old_start;
-	unsigned long new_start = old_start - shift;
-	unsigned long new_end = old_end - shift;
-	VMA_ITERATOR(vmi, mm, new_start);
-	struct vm_area_struct *next;
-	struct mmu_gather tlb;
-
-	BUG_ON(new_start > new_end);
-
-	/*
-	 * ensure there are no vmas between where we want to go
-	 * and where we are
-	 */
-	if (vma != vma_next(&vmi))
-		return -EFAULT;
-
-	vma_iter_prev_range(&vmi);
-	/*
-	 * cover the whole range: [new_start, old_end)
-	 */
-	if (vma_expand(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
-		return -ENOMEM;
-
-	/*
-	 * move the page tables downwards, on failure we rely on
-	 * process cleanup to remove whatever mess we made.
-	 */
-	if (length != move_page_tables(vma, old_start,
-				       vma, new_start, length, false, true))
-		return -ENOMEM;
-
-	lru_add_drain();
-	tlb_gather_mmu(&tlb, mm);
-	next = vma_next(&vmi);
-	if (new_end > old_start) {
-		/*
-		 * when the old and new regions overlap clear from new_end.
-		 */
-		free_pgd_range(&tlb, new_end, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	} else {
-		/*
-		 * otherwise, clean from old_start; this is done to not touch
-		 * the address space in [new_end, old_start) some architectures
-		 * have constraints on va-space that make this illegal (IA64) -
-		 * for the others its just a little faster.
-		 */
-		free_pgd_range(&tlb, old_start, old_end, new_end,
-			next ? next->vm_start : USER_PGTABLES_CEILING);
-	}
-	tlb_finish_mmu(&tlb);
-
-	vma_prev(&vmi);
-	/* Shrink the vma to just the new range */
-	return vma_shrink(&vmi, vma, new_start, new_end, vma->vm_pgoff);
Quoted 8 lines

fs/exec.c static int copy_strings_kernel(int argc, const char *const *argv, · line 691

Quoted 2 lines
fs/exec.c +1 -0
+	return relocate_vma(vma, shift);
 }

The end result is a function that simply returns the results of your new function. shift_arg_pages() is used once and mentioned in a single comment in mm/mremap.c. I wonder if it's worth just dropping the function entirely and just replacing the call to shift_arg_pages() to relocate_vma()?

Yeah that's a good idea, will do. Can move the comment over to the invocation also.

Quoted 22 lines

I'm happy either way, the compiler should do the Right Thing(tm) the way it is written.

...

fs/exec.c static int copy_strings_kernel(int argc, const char *const *argv,

Quoted 10 lines
fs/exec.c +10 -0
+
+/*
+ * Relocate a VMA downwards by shift bytes. There cannot be any VMAs between
+ * this VMA and its relocated range, which will now reside at [vma->vm_start -
+ * shift, vma->vm_end - shift).
+ *
+ * This function is almost certainly NOT what you want for anything other than
+ * early executable temporary stack relocation.
+ */
+int relocate_vma(struct vm_area_struct *vma, unsigned long shift)

The name relocate_vma() implies it could be used in any direction, but it can only shift downwards. This is also true for the shift_arg_pages() as well and at least the comments state which way things are going, and that the vma is also moving.

Quoted 5 lines

It might be worth stating the pages are also being relocated in the comment.

Again, I'm happy enough to keep it this way but I wanted to point it out.

Yeah, amusingly I was thinking about this when I wrote this, but worried that relocate_vma_down() would be overwrought. However on second thoughts I think you're right, this isn't ideal. Will change.

Also ack re: comment.

Quoted 5 lines

...

Thanks,
Liam

#8 lore raw

Re: [RFC PATCH v2 4/7] mm: move internal core VMA manipulation functions to own file

In reply to Liam R. Howlett
Quoted 41 lines · Liam R. Howlett
Quoted 30 lines · Lorenzo Stoakes

This patch introduces vma.c and moves internal core VMA manipulation functions to this file from mmap.c.

This allows us to isolate VMA functionality in a single place such that we can create userspace testing code that invokes this functionality in an environment where we can implement simple unit tests of core functionality.

This patch ensures that core VMA functionality is explicitly marked as such by its presence in mm/vma.h.

It also places the header includes required by vma.c in vma_internal.h, which is simply imported by vma.c. This makes the VMA functionality testable, as userland testing code can simply stub out functionality as required.

---
 include/linux/mm.h |   35 -
 mm/Makefile        |    2 +-
 mm/internal.h      |  236 +-----
 mm/mmap.c          | 1981 +++-----------------------------------------
 mm/mmu_notifier.c  |    2 +
 mm/vma.c           | 1766 +++++++++++++++++++++++++++++++++++++++
 mm/vma.h           |  362 ++++++++
 mm/vma_internal.h  |   52 ++
 8 files changed, 2293 insertions(+), 2143 deletions(-)
 create mode 100644 mm/vma.c
 create mode 100644 mm/vma.h
 create mode 100644 mm/vma_internal.h

...

Quoted 7 lines
mm/mmap.c +0 -0
index d2eebbed87b9..721870f380bf 100644
@@ -57,6 +57,7 @@
 #include <trace/events/mmap.h>
 
Quoted 4 lines

mm/mmap.c line 60

Quoted 2 lines
mm/mmap.c +1 -0
 #include "internal.h"
+#include "vma.h"

This isn't needed as internal.h includes vma.h in this revision.

Ugh yeah thought I caught all of them but clearly not. Will fix!

Quoted 9 lines

mm/mmap.c line 63

Quoted 4 lines
mm/mmap.c +0 -0
 #ifndef arch_mmap_check
 #define arch_mmap_check(addr, len, flags)	(0)

...

Thanks,
Liam

#11 lore raw

Re: [RFC PATCH v2 5/7] MAINTAINERS: Add entry for new VMA files

In reply to SeongJae Park
Quoted 20 lines · SeongJae Park

Hi Lorenzo,

Quoted 16 lines · On Fri, 28 Jun 2024 15:35:26 +0100 Lorenzo Stoakes <[email protected]> wrote:

The vma files contain logic split from mmap.c for the most part and are all relevant to VMA logic, so maintain the same reviewers for both.

---
 MAINTAINERS | 13 +++++++++++++
 1 file changed, 13 insertions(+)
MAINTAINERS +0 -0
index 098d214f78d9..0847cb5903ab 100644
@@ -23971,6 +23971,19 @@ F:	include/uapi/linux/vsockmon.h
 F:	net/vmw_vsock/
 F:	tools/testing/vsock/
 
Quoted 10 lines

MAINTAINERS F: include/uapi/linux/vsockmon.h · line 23981

Quoted 8 lines
MAINTAINERS +8 -0
+VMA
+M:	Andrew Morton <[email protected]>
+R:	Liam R. Howlett <[email protected]>
+R:	Vlastimil Babka <[email protected]>
+R:	Lorenzo Stoakes <[email protected]>
+L:	[email protected]
+S:	Maintained
+W:	http://www.linux-mm.org

I know this is just copy-pasted. But, what about using https instead of http?

Sure will update.

Quoted 17 lines
Quoted 10 lines
MAINTAINERS +5 -1
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
+F:	mm/vma.c
+F:	mm/vma.h
+F:	mm/vma_internal.h
+
 VMALLOC
 M:	Andrew Morton <[email protected]>
 R:	Uladzislau Rezki <[email protected]>
--
Quoted 3 lines

2.45.1

Thanks,
SJ

#15 lore raw

Re: [RFC PATCH v2 7/7] tools: add skeleton code for userland testing of VMA logic

In reply to SeongJae Park
Quoted 53 lines · SeongJae Park

Hi Lorenzo,

Quoted 40 lines · On Fri, 28 Jun 2024 15:35:28 +0100 Lorenzo Stoakes <[email protected]> wrote:

Establish a new userland VMA unit testing implementation under tools/testing which utilises existing logic providing maple tree support in userland utilising the now-shared code previously exclusive to radix tree testing.

This provides fundamental VMA operations whose API is defined in mm/vma.h, while stubbing out superfluous functionality.

This exists as a proof-of-concept, with the test implementation functional and sufficient to allow userland compilation of vma.c, but containing only cursory tests to demonstrate basic functionality.

---
 MAINTAINERS                            |   1 +
 include/linux/atomic.h                 |   2 +-
 include/linux/mmzone.h                 |   3 +-
 tools/testing/vma/.gitignore           |   6 +
 tools/testing/vma/Makefile             |  15 +
 tools/testing/vma/errors.txt           |   0
 tools/testing/vma/generated/autoconf.h |   2 +
 tools/testing/vma/linux/atomic.h       |  12 +
 tools/testing/vma/linux/mmzone.h       |  38 ++
 tools/testing/vma/vma.c                | 207 ++++++
 tools/testing/vma/vma_internal.h       | 882 +++++++++++++++++++++++++
 11 files changed, 1166 insertions(+), 2 deletions(-)
 create mode 100644 tools/testing/vma/.gitignore
 create mode 100644 tools/testing/vma/Makefile
 create mode 100644 tools/testing/vma/errors.txt
 create mode 100644 tools/testing/vma/generated/autoconf.h
 create mode 100644 tools/testing/vma/linux/atomic.h
 create mode 100644 tools/testing/vma/linux/mmzone.h
 create mode 100644 tools/testing/vma/vma.c
 create mode 100644 tools/testing/vma/vma_internal.h
MAINTAINERS +0 -0
index 0847cb5903ab..410062bd8e21 100644

MAINTAINERS T: git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm · line 23986

Quoted 4 lines
MAINTAINERS +1 -0
@@ -23983,6 +23983,7 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
 F:	mm/vma.c
 F:	mm/vma.h
 F:	mm/vma_internal.h
+F:	tools/testing/vma

According to the description of 'F:' section description at the beginning of this file (quoting below), I think adding a trailing slash to the above line would be nice?

Quoted 5 lines

F: *Files* and directories wildcard patterns.
A trailing slash includes all files and subdirectory files.
F: drivers/net/ all files in and below drivers/net

Ack will update.

Quoted 4 lines

Thanks,
SJ

[...]

#16 lore raw
In reply to Lorenzo Stoakes
Quoted 50 lines · Lorenzo Stoakes

There are a number of "core" VMA manipulation functions implemented in mm/mmap.c, notably those concerning VMA merging, splitting, modifying, expanding and shrinking, which logically don't belong there.

More importantly this functionality represents an internal implementation detail of memory management and should not be exposed outside of mm/ itself.

This patch series isolates core VMA manipulation functionality into its own file, mm/vma.c, and provides an API to the rest of the mm code in mm/vma.h.

Importantly, it also carefully implements mm/vma_internal.h, which specifies which headers need to be imported by vma.c, leading to the very useful property that vma.c depends only on mm/vma.h and mm/vma_internal.h.

This is useful, because we can then re-implement vma_internal.h in userland, stubbing out and adding shims for kernel mechanisms as required, and then can directly and very easily unit test internal VMA functionality.

This patch series takes advantage of existing shim logic and full userland maple tree support contained in tools/testing/radix-tree/ and tools/include/linux/, separating out shared components of the radix tree implementation to provide this testing.

Kernel functionality is stubbed and shimmed as needed in tools/testing/vma/ which contains a fully functional userland vma_internal.h file and which imports mm/vma.c and mm/vma.h to be directly tested from userland.

A simple, skeleton testing implementation is provided in tools/testing/vma/vma.c as a proof-of-concept, asserting that simple VMA merge, modify (testing split), expand and shrink functionality work correctly.

v2:
* Reword commit messages.
* Replace vma_expand() / vma_shrink() wrappers with relocate_vma().
* Make move_page_tables() internal too.
* Have internal.h import vma.h.
* Use header guards to more cleanly implement userland testing code.
* Rename main.c to vma.c.
* Update mm/vma_internal.h to have fewer superfluous comments.
* Rework testing logic so we count test failures, and output test results.
* Correct some SPDX license prefixes.
* Make VM_xxx_ON() debug asserts forward to xxx_ON() macros.
* Update VMA tests to correctly free memory, and re-enable ASAN leak detection.

v1:
https://lore.kernel.org/all/[email protected]/

Quoted 9 lines

Lorenzo Stoakes (7):
userfaultfd: move core VMA manipulation logic to mm/userfaultfd.c
mm: move vma_modify() and helpers to internal header
mm: move vma_shrink(), vma_expand() to internal header
mm: move internal core VMA manipulation functions to own file
MAINTAINERS: Add entry for new VMA files
tools: separate out shared radix-tree components
tools: add skeleton code for userland testing of VMA logic

As this is stabilising and there seems to be no major objections, the next re-spin will be sent un-RFC'd.

I have a few small fixes on the userland testing code I will include, in addition to the stuff commented on here.

Quoted 91 lines
 MAINTAINERS                                   |   14 +
 fs/exec.c                                     |   68 +-
 fs/userfaultfd.c                              |  160 +-
 include/linux/atomic.h                        |    2 +-
 include/linux/mm.h                            |  112 +-
 include/linux/mmzone.h                        |    3 +-
 include/linux/userfaultfd_k.h                 |   19 +
 mm/Makefile                                   |    2 +-
 mm/internal.h                                 |  167 +-
 mm/mmap.c                                     | 2070 ++---------------
 mm/mmu_notifier.c                             |    2 +
 mm/userfaultfd.c                              |  168 ++
 mm/vma.c                                      | 1766 ++++++++++++++
 mm/vma.h                                      |  362 +++
 mm/vma_internal.h                             |   52 +
 tools/testing/radix-tree/Makefile             |   68 +-
 tools/testing/radix-tree/maple.c              |   14 +-
 tools/testing/radix-tree/xarray.c             |    9 +-
 tools/testing/shared/autoconf.h               |    2 +
 tools/testing/{radix-tree => shared}/bitmap.c |    0
 tools/testing/{radix-tree => shared}/linux.c  |    0
 .../{radix-tree => shared}/linux/bug.h        |    0
 .../{radix-tree => shared}/linux/cpu.h        |    0
 .../{radix-tree => shared}/linux/idr.h        |    0
 .../{radix-tree => shared}/linux/init.h       |    0
 .../{radix-tree => shared}/linux/kconfig.h    |    0
 .../{radix-tree => shared}/linux/kernel.h     |    0
 .../{radix-tree => shared}/linux/kmemleak.h   |    0
 .../{radix-tree => shared}/linux/local_lock.h |    0
 .../{radix-tree => shared}/linux/lockdep.h    |    0
 .../{radix-tree => shared}/linux/maple_tree.h |    0
 .../{radix-tree => shared}/linux/percpu.h     |    0
 .../{radix-tree => shared}/linux/preempt.h    |    0
 .../{radix-tree => shared}/linux/radix-tree.h |    0
 .../{radix-tree => shared}/linux/rcupdate.h   |    0
 .../{radix-tree => shared}/linux/xarray.h     |    0
 tools/testing/shared/maple-shared.h           |    9 +
 tools/testing/shared/maple-shim.c             |    7 +
 tools/testing/shared/shared.h                 |   34 +
 tools/testing/shared/shared.mk                |   68 +
 .../testing/shared/trace/events/maple_tree.h  |    5 +
 tools/testing/shared/xarray-shared.c          |    5 +
 tools/testing/shared/xarray-shared.h          |    4 +
 tools/testing/vma/.gitignore                  |    6 +
 tools/testing/vma/Makefile                    |   15 +
 tools/testing/vma/errors.txt                  |    0
 tools/testing/vma/generated/autoconf.h        |    2 +
 tools/testing/vma/linux/atomic.h              |   12 +
 tools/testing/vma/linux/mmzone.h              |   38 +
 tools/testing/vma/vma.c                       |  207 ++
 tools/testing/vma/vma_internal.h              |  882 +++++++
 51 files changed, 3910 insertions(+), 2444 deletions(-)
 create mode 100644 mm/vma.c
 create mode 100644 mm/vma.h
 create mode 100644 mm/vma_internal.h
 create mode 100644 tools/testing/shared/autoconf.h
 rename tools/testing/{radix-tree => shared}/bitmap.c (100%)
 rename tools/testing/{radix-tree => shared}/linux.c (100%)
 rename tools/testing/{radix-tree => shared}/linux/bug.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/cpu.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/idr.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/init.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kconfig.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kernel.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/kmemleak.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/local_lock.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/lockdep.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/maple_tree.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/percpu.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/preempt.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/radix-tree.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/rcupdate.h (100%)
 rename tools/testing/{radix-tree => shared}/linux/xarray.h (100%)
 create mode 100644 tools/testing/shared/maple-shared.h
 create mode 100644 tools/testing/shared/maple-shim.c
 create mode 100644 tools/testing/shared/shared.h
 create mode 100644 tools/testing/shared/shared.mk
 create mode 100644 tools/testing/shared/trace/events/maple_tree.h
 create mode 100644 tools/testing/shared/xarray-shared.c
 create mode 100644 tools/testing/shared/xarray-shared.h
 create mode 100644 tools/testing/vma/.gitignore
 create mode 100644 tools/testing/vma/Makefile
 create mode 100644 tools/testing/vma/errors.txt
 create mode 100644 tools/testing/vma/generated/autoconf.h
 create mode 100644 tools/testing/vma/linux/atomic.h
 create mode 100644 tools/testing/vma/linux/mmzone.h
 create mode 100644 tools/testing/vma/vma.c
 create mode 100644 tools/testing/vma/vma_internal.h

--
2.45.1