[v3] mm, slab: Check GFP_SLAB_BUG_MASK before alloc_pages in kmalloc_order
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Message ID 20200701151645.GA26223@lilong
State In Next
Commit b045078df2d3d305c7377e8f3404a7a3ffbd920a
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Series
  • [v3] mm, slab: Check GFP_SLAB_BUG_MASK before alloc_pages in kmalloc_order
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Commit Message

Long Li July 1, 2020, 3:16 p.m. UTC
kmalloc cannot allocate memory from HIGHMEM.  Allocating large amounts
of memory currently bypasses the check and will simply leak the memory
when page_address() returns NULL.  To fix this, factor the
GFP_SLAB_BUG_MASK check out of slab & slub, and call it from
kmalloc_order() as well. In order to make the code clear, the warning
message is put in one place.

Signed-off-by: Long Li <lonuxli.64@gmail.com>
---

changes in V3:
-Put the warning message in one place
-updage the change log to be clear

 mm/slab.c        | 10 +++-------
 mm/slab.h        |  1 +
 mm/slab_common.c | 17 +++++++++++++++++
 mm/slub.c        |  9 ++-------
 4 files changed, 23 insertions(+), 14 deletions(-)

Comments

Matthew Wilcox July 1, 2020, 3:24 p.m. UTC | #1
On Wed, Jul 01, 2020 at 03:16:45PM +0000, Long Li wrote:
> kmalloc cannot allocate memory from HIGHMEM.  Allocating large amounts
> of memory currently bypasses the check and will simply leak the memory
> when page_address() returns NULL.  To fix this, factor the
> GFP_SLAB_BUG_MASK check out of slab & slub, and call it from
> kmalloc_order() as well. In order to make the code clear, the warning
> message is put in one place.
> 
> Signed-off-by: Long Li <lonuxli.64@gmail.com>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Pekka Enberg July 1, 2020, 3:47 p.m. UTC | #2
On Wed, Jul 1, 2020 at 6:19 PM Long Li <lonuxli.64@gmail.com> wrote:
>
> kmalloc cannot allocate memory from HIGHMEM.  Allocating large amounts
> of memory currently bypasses the check and will simply leak the memory
> when page_address() returns NULL.  To fix this, factor the
> GFP_SLAB_BUG_MASK check out of slab & slub, and call it from
> kmalloc_order() as well. In order to make the code clear, the warning
> message is put in one place.
>
> Signed-off-by: Long Li <lonuxli.64@gmail.com>

Reviewed-by: Pekka Enberg <penberg@kernel.org>
David Rientjes July 1, 2020, 6:52 p.m. UTC | #3
On Wed, 1 Jul 2020, Long Li wrote:

> diff --git a/mm/slab.c b/mm/slab.c
> index ac7a223d9ac3..2850fe3c5fb8 100644
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -2573,13 +2573,9 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep,
>  	 * Be lazy and only check for valid flags here,  keeping it out of the
>  	 * critical path in kmem_cache_alloc().
>  	 */
> -	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
> -		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
> -		flags &= ~GFP_SLAB_BUG_MASK;
> -		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
> -				invalid_mask, &invalid_mask, flags, &flags);
> -		dump_stack();
> -	}
> +	if (unlikely(flags & GFP_SLAB_BUG_MASK))
> +		flags = kmalloc_invalid_flags(flags);
> +
>  	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
>  	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
>  

Is this name correct?  kmalloc_invalid_flags() masks off the invalid flags 
and returns the valid flags :)  Maybe kmalloc_check_flags()?

Patch
diff mbox series

diff --git a/mm/slab.c b/mm/slab.c
index ac7a223d9ac3..2850fe3c5fb8 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2573,13 +2573,9 @@  static struct page *cache_grow_begin(struct kmem_cache *cachep,
 	 * Be lazy and only check for valid flags here,  keeping it out of the
 	 * critical path in kmem_cache_alloc().
 	 */
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		flags = kmalloc_invalid_flags(flags);
+
 	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
 	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
diff --git a/mm/slab.h b/mm/slab.h
index a06f3313e4a0..ab172dca8ce2 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -90,6 +90,7 @@  void create_kmalloc_caches(slab_flags_t);
 struct kmem_cache *kmalloc_slab(size_t, gfp_t);
 #endif
 
+gfp_t kmalloc_invalid_flags(gfp_t flags);
 
 /* Functions provided by the slab allocators */
 int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index a143a8c8f874..85a16e323906 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -26,6 +26,8 @@ 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kmem.h>
 
+#include "internal.h"
+
 #include "slab.h"
 
 enum slab_state slab_state;
@@ -805,6 +807,18 @@  void __init create_kmalloc_caches(slab_flags_t flags)
 }
 #endif /* !CONFIG_SLOB */
 
+gfp_t kmalloc_invalid_flags(gfp_t flags)
+{
+	gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
+
+	flags &= ~GFP_SLAB_BUG_MASK;
+	pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
+			invalid_mask, &invalid_mask, flags, &flags);
+	dump_stack();
+
+	return flags;
+}
+
 /*
  * To avoid unnecessary overhead, we pass through large allocation requests
  * directly to the page allocator. We use __GFP_COMP, because we will need to
@@ -815,6 +829,9 @@  void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
 	void *ret = NULL;
 	struct page *page;
 
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		flags = kmalloc_invalid_flags(flags);
+
 	flags |= __GFP_COMP;
 	page = alloc_pages(flags, order);
 	if (likely(page)) {
diff --git a/mm/slub.c b/mm/slub.c
index 62d2de56549e..039045211df9 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1817,13 +1817,8 @@  static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 
 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 {
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		flags = kmalloc_invalid_flags(flags);
 
 	return allocate_slab(s,
 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);