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FAILED: patch "[PATCH] mm/vmalloc, mm/kasan: respect gfp mask in" failed to apply to 6.6-stable tree

PATCH [email protected] 1 participant 1 message Sep 13, 2025

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The patch below does not apply to the 6.6-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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 79357cd06d41d0f5a11b17d7c86176e395d10ef2
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025091303-frill-pacemaker-0871@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From 79357cd06d41d0f5a11b17d7c86176e395d10ef2 Mon Sep 17 00:00:00 2001
From: "Uladzislau Rezki (Sony)" <[email protected]>
Date: Sun, 31 Aug 2025 14:10:58 +0200
Subject: [PATCH] mm/vmalloc, mm/kasan: respect gfp mask in
kasan_populate_vmalloc()

kasan_populate_vmalloc() and its helpers ignore the caller's gfp_mask and always allocate memory using the hardcoded GFP_KERNEL flag. This makes them inconsistent with vmalloc(), which was recently extended to support GFP_NOFS and GFP_NOIO allocations.

Page table allocations performed during shadow population also ignore the external gfp_mask. To preserve the intended semantics of GFP_NOFS and GFP_NOIO, wrap the apply_to_page_range() calls into the appropriate memalloc scope.

xfs calls vmalloc with GFP_NOFS, so this bug could lead to deadlock.

There was a report here
https://lkml.kernel.org/r/[email protected]

This patch:
- Extends kasan_populate_vmalloc() and helpers to take gfp_mask;
- Passes gfp_mask down to alloc_pages_bulk() and __get_free_page();
- Enforces GFP_NOFS/NOIO semantics with memalloc_*_save()/restore() around apply_to_page_range();
- Updates vmalloc.c and percpu allocator call sites accordingly.

Link https://lkml.kernel.org/r/[email protected] open here
Fixes 451769ebb7e7 ("mm/vmalloc: alloc GFP_NO{FS,IO} for vmalloc")
Signed-off-by Uladzislau Rezki (Sony) <[email protected]>
Reported-by [email protected]
Reviewed-by Andrey Ryabinin <[email protected]>
Cc Baoquan He <[email protected]>
Cc Michal Hocko <[email protected]>
Cc Alexander Potapenko <[email protected]>
Cc Andrey Konovalov <[email protected]>
Cc Dmitry Vyukov <[email protected]>
Cc Vincenzo Frascino <[email protected]>
Cc <[email protected]>
Signed-off-by Andrew Morton <[email protected]>
include/linux/kasan.h +3 -3
index 890011071f2b..fe5ce9215821 100644
@@ -562,7 +562,7 @@ static inline void kasan_init_hw_tags(void) { }
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 
 void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
-int kasan_populate_vmalloc(unsigned long addr, unsigned long size);
+int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask);
 void kasan_release_vmalloc(unsigned long start, unsigned long end,
 			   unsigned long free_region_start,
 			   unsigned long free_region_end,

@@ -574,7 +574,7 @@ static inline void kasan_populate_early_vm_area_shadow(void *start,
 						       unsigned long size)
 { }
 static inline int kasan_populate_vmalloc(unsigned long start,
-					unsigned long size)
+					unsigned long size, gfp_t gfp_mask)
 {
 	return 0;
 }

@@ -610,7 +610,7 @@ static __always_inline void kasan_poison_vmalloc(const void *start,
 static inline void kasan_populate_early_vm_area_shadow(void *start,
 						       unsigned long size) { }
 static inline int kasan_populate_vmalloc(unsigned long start,
-					unsigned long size)
+					unsigned long size, gfp_t gfp_mask)
 {
 	return 0;
 }
mm/kasan/shadow.c +24 -7
index e2ceebf737ef..11d472a5c4e8 100644
@@ -336,13 +336,13 @@ static void ___free_pages_bulk(struct page **pages, int nr_pages)
 	}
 }
 
-static int ___alloc_pages_bulk(struct page **pages, int nr_pages)
+static int ___alloc_pages_bulk(struct page **pages, int nr_pages, gfp_t gfp_mask)
 {
 	unsigned long nr_populated, nr_total = nr_pages;
 	struct page **page_array = pages;
 
 	while (nr_pages) {
-		nr_populated = alloc_pages_bulk(GFP_KERNEL, nr_pages, pages);
+		nr_populated = alloc_pages_bulk(gfp_mask, nr_pages, pages);
 		if (!nr_populated) {
 			___free_pages_bulk(page_array, nr_total - nr_pages);
 			return -ENOMEM;

@@ -354,25 +354,42 @@ static int ___alloc_pages_bulk(struct page **pages, int nr_pages)
 	return 0;
 }
 
-static int __kasan_populate_vmalloc(unsigned long start, unsigned long end)
+static int __kasan_populate_vmalloc(unsigned long start, unsigned long end, gfp_t gfp_mask)
 {
 	unsigned long nr_pages, nr_total = PFN_UP(end - start);
 	struct vmalloc_populate_data data;
+	unsigned int flags;
 	int ret = 0;
 
-	data.pages = (struct page **)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+	data.pages = (struct page **)__get_free_page(gfp_mask | __GFP_ZERO);
 	if (!data.pages)
 		return -ENOMEM;
 
 	while (nr_total) {
 		nr_pages = min(nr_total, PAGE_SIZE / sizeof(data.pages[0]));
-		ret = ___alloc_pages_bulk(data.pages, nr_pages);
+		ret = ___alloc_pages_bulk(data.pages, nr_pages, gfp_mask);
 		if (ret)
 			break;
 
 		data.start = start;
+
+		/*
+		 * page tables allocations ignore external gfp mask, enforce it
+		 * by the scope API
+		 */
+		if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
+			flags = memalloc_nofs_save();
+		else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
+			flags = memalloc_noio_save();
+
 		ret = apply_to_page_range(&init_mm, start, nr_pages * PAGE_SIZE,
 					  kasan_populate_vmalloc_pte, &data);
+
+		if ((gfp_mask & (__GFP_FS | __GFP_IO)) == __GFP_IO)
+			memalloc_nofs_restore(flags);
+		else if ((gfp_mask & (__GFP_FS | __GFP_IO)) == 0)
+			memalloc_noio_restore(flags);
+
 		___free_pages_bulk(data.pages, nr_pages);
 		if (ret)
 			break;

@@ -386,7 +403,7 @@ static int __kasan_populate_vmalloc(unsigned long start, unsigned long end)
 	return ret;
 }
 
-int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
+int kasan_populate_vmalloc(unsigned long addr, unsigned long size, gfp_t gfp_mask)
 {
 	unsigned long shadow_start, shadow_end;
 	int ret;

@@ -415,7 +432,7 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
 	shadow_start = PAGE_ALIGN_DOWN(shadow_start);
 	shadow_end = PAGE_ALIGN(shadow_end);
 
-	ret = __kasan_populate_vmalloc(shadow_start, shadow_end);
+	ret = __kasan_populate_vmalloc(shadow_start, shadow_end, gfp_mask);
 	if (ret)
 		return ret;
mm/vmalloc.c +4 -4
index 6dbcdceecae1..5edd536ba9d2 100644
@@ -2026,6 +2026,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
 	if (unlikely(!vmap_initialized))
 		return ERR_PTR(-EBUSY);
 
+	/* Only reclaim behaviour flags are relevant. */
+	gfp_mask = gfp_mask & GFP_RECLAIM_MASK;
 	might_sleep();
 
 	/*

@@ -2038,8 +2040,6 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
 	 */
 	va = node_alloc(size, align, vstart, vend, &addr, &vn_id);
 	if (!va) {
-		gfp_mask = gfp_mask & GFP_RECLAIM_MASK;
-
 		va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node);
 		if (unlikely(!va))
 			return ERR_PTR(-ENOMEM);

@@ -2089,7 +2089,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
 	BUG_ON(va->va_start < vstart);
 	BUG_ON(va->va_end > vend);
 
-	ret = kasan_populate_vmalloc(addr, size);
+	ret = kasan_populate_vmalloc(addr, size, gfp_mask);
 	if (ret) {
 		free_vmap_area(va);
 		return ERR_PTR(ret);

@@ -4826,7 +4826,7 @@ struct vm_struct **pcpu_get_vm_areas(const unsigned long *offsets,
 
 	/* populate the kasan shadow space */
 	for (area = 0; area < nr_vms; area++) {
-		if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area]))
+		if (kasan_populate_vmalloc(vas[area]->va_start, sizes[area], GFP_KERNEL))
 			goto err_free_shadow;
 	}