Skip to contentSkip to conversation

FAILED: patch "[PATCH] mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 2 messages Nov 11, 2024 – Nov 14, 2024

Subsystems (6)
Stable branch Memory management arm64 Memory mapping +2 more subsystems
lore
Share & tools
lore

[email protected]

author maintainer
#0 lore raw

The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x 5baf8b037debf4ec60108ccfeccb8636d1dbad81
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2024111139-gladiator-wavy-a9d1@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 5baf8b037debf4ec60108ccfeccb8636d1dbad81 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <[email protected]>
Date: Tue, 29 Oct 2024 18:11:47 +0000
Subject: [PATCH] mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling

Currently MTE is permitted in two circumstances (desiring to use MTE having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is specified, as checked by arch_calc_vm_flag_bits() and actualised by setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap hook is activated in mmap_region().

The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also set is the arm64 implementation of arch_validate_flags().

Unfortunately, we intend to refactor mmap_region() to perform this check earlier, meaning that in the case of a shmem backing we will not have invoked shmem_mmap() yet, causing the mapping to fail spuriously.

It is inappropriate to set this architecture-specific flag in general mm code anyway, so a sensible resolution of this issue is to instead move the check somewhere else.

We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via the arch_calc_vm_flag_bits() call.

This is an appropriate place to do this as we already check for the MAP_ANONYMOUS case here, and the shmem file case is simply a variant of the same idea - we permit RAM-backed memory.

This requires a modification to the arch_calc_vm_flag_bits() signature to pass in a pointer to the struct file associated with the mapping, however this is not too egregious as this is only used by two architectures anyway
- arm64 and parisc.

So this patch performs this adjustment and removes the unnecessary assignment of VM_MTE_ALLOWED in shmem_mmap().

[[email protected]: fix whitespace, per Catalin]
Link https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com open here
Fixes deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails")
Signed-off-by Lorenzo Stoakes <[email protected]>
Suggested-by Catalin Marinas <[email protected]>
Reported-by Jann Horn <[email protected]>
Reviewed-by Catalin Marinas <[email protected]>
Reviewed-by Vlastimil Babka <[email protected]>
Cc Andreas Larsson <[email protected]>
Cc David S. Miller <[email protected]>
Cc Helge Deller <[email protected]>
Cc James E.J. Bottomley <[email protected]>
Cc Liam R. Howlett <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Mark Brown <[email protected]>
Cc Peter Xu <[email protected]>
Cc Will Deacon <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
arch/arm64/include/asm/mman.h +7 -3
index 9e39217b4afb..798d965760d4 100644
@@ -6,6 +6,8 @@
 
 #ifndef BUILD_VDSO
 #include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/shmem_fs.h>
 #include <linux/types.h>
 
 static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,

@@ -31,19 +33,21 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
 }
 #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
 
-static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags)
+static inline unsigned long arch_calc_vm_flag_bits(struct file *file,
+						   unsigned long flags)
 {
 	/*
 	 * Only allow MTE on anonymous mappings as these are guaranteed to be
 	 * backed by tags-capable memory. The vm_flags may be overridden by a
 	 * filesystem supporting MTE (RAM-based).
 	 */
-	if (system_supports_mte() && (flags & MAP_ANONYMOUS))
+	if (system_supports_mte() &&
+	    ((flags & MAP_ANONYMOUS) || shmem_file(file)))
 		return VM_MTE_ALLOWED;
 
 	return 0;
 }
-#define arch_calc_vm_flag_bits(flags) arch_calc_vm_flag_bits(flags)
+#define arch_calc_vm_flag_bits(file, flags) arch_calc_vm_flag_bits(file, flags)
 
 static inline bool arch_validate_prot(unsigned long prot,
 	unsigned long addr __always_unused)
arch/parisc/include/asm/mman.h +3 -2
index 89b6beeda0b8..663f587dc789 100644
@@ -2,6 +2,7 @@
 #ifndef __ASM_MMAN_H__
 #define __ASM_MMAN_H__
 
+#include <linux/fs.h>
 #include <uapi/asm/mman.h>
 
 /* PARISC cannot allow mdwe as it needs writable stacks */

@@ -11,7 +12,7 @@ static inline bool arch_memory_deny_write_exec_supported(void)
 }
 #define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported
 
-static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags)
+static inline unsigned long arch_calc_vm_flag_bits(struct file *file, unsigned long flags)
 {
 	/*
 	 * The stack on parisc grows upwards, so if userspace requests memory

@@ -23,6 +24,6 @@ static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags)
 
 	return 0;
 }
-#define arch_calc_vm_flag_bits(flags) arch_calc_vm_flag_bits(flags)
+#define arch_calc_vm_flag_bits(file, flags) arch_calc_vm_flag_bits(file, flags)
 
 #endif /* __ASM_MMAN_H__ */
include/linux/mman.h +4 -3
index 8ddca62d6460..a842783ffa62 100644
@@ -2,6 +2,7 @@
 #ifndef _LINUX_MMAN_H
 #define _LINUX_MMAN_H
 
+#include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/percpu_counter.h>
 

@@ -94,7 +95,7 @@ static inline void vm_unacct_memory(long pages)
 #endif
 
 #ifndef arch_calc_vm_flag_bits
-#define arch_calc_vm_flag_bits(flags) 0
+#define arch_calc_vm_flag_bits(file, flags) 0
 #endif
 
 #ifndef arch_validate_prot

@@ -151,13 +152,13 @@ calc_vm_prot_bits(unsigned long prot, unsigned long pkey)
  * Combine the mmap "flags" argument into "vm_flags" used internally.
  */
 static inline unsigned long
-calc_vm_flag_bits(unsigned long flags)
+calc_vm_flag_bits(struct file *file, unsigned long flags)
 {
 	return _calc_vm_trans(flags, MAP_GROWSDOWN,  VM_GROWSDOWN ) |
 	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
 	       _calc_vm_trans(flags, MAP_SYNC,	     VM_SYNC      ) |
 	       _calc_vm_trans(flags, MAP_STACK,	     VM_NOHUGEPAGE) |
-	       arch_calc_vm_flag_bits(flags);
+	       arch_calc_vm_flag_bits(file, flags);
 }
 
 unsigned long vm_commit_limit(void);
mm/mmap.c +1 -1
index ab71d4c3464c..aee5fa08ae5d 100644
@@ -344,7 +344,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 	 * to. we assume access permissions have been handled by the open
 	 * of the memory object, so we don't do any here.
 	 */
-	vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
+	vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(file, flags) |
 			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 
 	/* Obtain the address to map to. we verify (or select) it and ensure
mm/nommu.c +1 -1
index 635d028d647b..e9b5f527ab5b 100644
@@ -842,7 +842,7 @@ static unsigned long determine_vm_flags(struct file *file,
 {
 	unsigned long vm_flags;
 
-	vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
+	vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(file, flags);
 
 	if (!file) {
 		/*
mm/shmem.c +0 -3
index 4ba1d00fabda..e87f5d6799a7 100644
@@ -2733,9 +2733,6 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 	if (ret)
 		return ret;
 
-	/* arm64 - allow memory tagging on RAM-based files */
-	vm_flags_set(vma, VM_MTE_ALLOWED);
-
 	file_accessed(file);
 	/* This is anonymous shared memory if it is unlinked at the time of mmap */
 	if (inode->i_nlink)
#1 lore raw

PATCH 1/1 mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling

Currently MTE is permitted in two circumstances (desiring to use MTE having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is specified, as checked by arch_calc_vm_flag_bits() and actualised by setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap hook is activated in mmap_region().

The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also set is the arm64 implementation of arch_validate_flags().

Unfortunately, we intend to refactor mmap_region() to perform this check earlier, meaning that in the case of a shmem backing we will not have invoked shmem_mmap() yet, causing the mapping to fail spuriously.

It is inappropriate to set this architecture-specific flag in general mm code anyway, so a sensible resolution of this issue is to instead move the check somewhere else.

We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via the arch_calc_vm_flag_bits() call.

This is an appropriate place to do this as we already check for the MAP_ANONYMOUS case here, and the shmem file case is simply a variant of the same idea - we permit RAM-backed memory.

This requires a modification to the arch_calc_vm_flag_bits() signature to pass in a pointer to the struct file associated with the mapping, however this is not too egregious as this is only used by two architectures anyway
- arm64 and parisc.

So this patch performs this adjustment and removes the unnecessary assignment of VM_MTE_ALLOWED in shmem_mmap().

[[email protected]: fix whitespace, per Catalin]
Link https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com open here
Fixes deb0f6562884 ("mm/mmap: undo ->mmap() when arch_validate_flags() fails")
Signed-off-by Lorenzo Stoakes <[email protected]>
Suggested-by Catalin Marinas <[email protected]>
Reported-by Jann Horn <[email protected]>
Reviewed-by Catalin Marinas <[email protected]>
Reviewed-by Vlastimil Babka <[email protected]>
Cc Andreas Larsson <[email protected]>
Cc David S. Miller <[email protected]>
Cc Helge Deller <[email protected]>
Cc James E.J. Bottomley <[email protected]>
Cc Liam R. Howlett <[email protected]>
Cc Linus Torvalds <[email protected]>
Cc Mark Brown <[email protected]>
Cc Peter Xu <[email protected]>
Cc Will Deacon <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
(cherry picked from commit 5baf8b037debf4ec60108ccfeccb8636d1dbad81)
---
 arch/arm64/include/asm/mman.h | 10 +++++++---
 include/linux/mman.h          |  7 ++++---
 mm/mmap.c                     |  2 +-
 mm/nommu.c                    |  2 +-
 mm/shmem.c                    |  3 ---
 5 files changed, 13 insertions(+), 11 deletions(-)
arch/arm64/include/asm/mman.h +7 -3
index e3e28f7daf62..56bc2e4e81a6 100644
@@ -3,6 +3,8 @@
 #define __ASM_MMAN_H__
 
 #include <linux/compiler.h>
+#include <linux/fs.h>
+#include <linux/shmem_fs.h>
 #include <linux/types.h>
 #include <uapi/asm/mman.h>
 

@@ -21,19 +23,21 @@ static inline unsigned long arch_calc_vm_prot_bits(unsigned long prot,
 }
 #define arch_calc_vm_prot_bits(prot, pkey) arch_calc_vm_prot_bits(prot, pkey)
 
-static inline unsigned long arch_calc_vm_flag_bits(unsigned long flags)
+static inline unsigned long arch_calc_vm_flag_bits(struct file *file,
+						   unsigned long flags)
 {
 	/*
 	 * Only allow MTE on anonymous mappings as these are guaranteed to be
 	 * backed by tags-capable memory. The vm_flags may be overridden by a
 	 * filesystem supporting MTE (RAM-based).
 	 */
-	if (system_supports_mte() && (flags & MAP_ANONYMOUS))
+	if (system_supports_mte() &&
+	    ((flags & MAP_ANONYMOUS) || shmem_file(file)))
 		return VM_MTE_ALLOWED;
 
 	return 0;
 }
-#define arch_calc_vm_flag_bits(flags) arch_calc_vm_flag_bits(flags)
+#define arch_calc_vm_flag_bits(file, flags) arch_calc_vm_flag_bits(file, flags)
 
 static inline pgprot_t arch_vm_get_page_prot(unsigned long vm_flags)
 {
include/linux/mman.h +4 -3
index b66e91b8176c..c5569219de01 100644
@@ -2,6 +2,7 @@
 #ifndef _LINUX_MMAN_H
 #define _LINUX_MMAN_H
 
+#include <linux/fs.h>
 #include <linux/mm.h>
 #include <linux/percpu_counter.h>
 

@@ -90,7 +91,7 @@ static inline void vm_unacct_memory(long pages)
 #endif
 
 #ifndef arch_calc_vm_flag_bits
-#define arch_calc_vm_flag_bits(flags) 0
+#define arch_calc_vm_flag_bits(file, flags) 0
 #endif
 
 #ifndef arch_vm_get_page_prot

@@ -151,12 +152,12 @@ calc_vm_prot_bits(unsigned long prot, unsigned long pkey)
  * Combine the mmap "flags" argument into "vm_flags" used internally.
  */
 static inline unsigned long
-calc_vm_flag_bits(unsigned long flags)
+calc_vm_flag_bits(struct file *file, unsigned long flags)
 {
 	return _calc_vm_trans(flags, MAP_GROWSDOWN,  VM_GROWSDOWN ) |
 	       _calc_vm_trans(flags, MAP_LOCKED,     VM_LOCKED    ) |
 	       _calc_vm_trans(flags, MAP_SYNC,	     VM_SYNC      ) |
-	       arch_calc_vm_flag_bits(flags);
+	       arch_calc_vm_flag_bits(file, flags);
 }
 
 unsigned long vm_commit_limit(void);
mm/mmap.c +1 -1
index d19fdcf2aa26..a766b1c1af32 100644
@@ -1466,7 +1466,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
 	 * to. we assume access permissions have been handled by the open
 	 * of the memory object, so we don't do any here.
 	 */
-	vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
+	vm_flags = calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(file, flags) |
 			mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 
 	if (flags & MAP_LOCKED)
mm/nommu.c +1 -1
index 084dd593913e..8b5c95528b00 100644
@@ -906,7 +906,7 @@ static unsigned long determine_vm_flags(struct file *file,
 {
 	unsigned long vm_flags;
 
-	vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags);
+	vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(file, flags);
 	/* vm_flags |= mm->def_flags; */
 
 	if (!(capabilities & NOMMU_MAP_DIRECT)) {
mm/shmem.c +0 -3
index cdb169348ba9..81da2c3debdf 100644
@@ -2268,9 +2268,6 @@ static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
 	if (ret)
 		return ret;
 
-	/* arm64 - allow memory tagging on RAM-based files */
-	vma->vm_flags |= VM_MTE_ALLOWED;
-
 	file_accessed(file);
 	vma->vm_ops = &shmem_vm_ops;
 	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
Signature · 1 line
2.47.0