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authorDmitry Vyukov <dvyukov@google.com>2018-10-26 15:03:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-10-26 16:25:19 -0700
commit61448479a9f2c954cde0cfe778cb6bec5d0a748d (patch)
tree4c549b9918e7652c7fe73701eef9a7c6f5555e08 /mm/slab_common.c
parent0684e6526edfb4debf0a0a884834bb1a104085dc (diff)
downloadlinux-61448479a9f2c954cde0cfe778cb6bec5d0a748d.tar.bz2
mm: don't warn about large allocations for slab
Slub does not call kmalloc_slab() for sizes > KMALLOC_MAX_CACHE_SIZE, instead it falls back to kmalloc_large(). For slab KMALLOC_MAX_CACHE_SIZE == KMALLOC_MAX_SIZE and it calls kmalloc_slab() for all allocations relying on NULL return value for over-sized allocations. This inconsistency leads to unwanted warnings from kmalloc_slab() for over-sized allocations for slab. Returning NULL for failed allocations is the expected behavior. Make slub and slab code consistent by checking size > KMALLOC_MAX_CACHE_SIZE in slab before calling kmalloc_slab(). While we are here also fix the check in kmalloc_slab(). We should check against KMALLOC_MAX_CACHE_SIZE rather than KMALLOC_MAX_SIZE. It all kinda worked because for slab the constants are the same, and slub always checks the size against KMALLOC_MAX_CACHE_SIZE before kmalloc_slab(). But if we get there with size > KMALLOC_MAX_CACHE_SIZE anyhow bad things will happen. For example, in case of a newly introduced bug in slub code. Also move the check in kmalloc_slab() from function entry to the size > 192 case. This partially compensates for the additional check in slab code and makes slub code a bit faster (at least theoretically). Also drop __GFP_NOWARN in the warning check. This warning means a bug in slab code itself, user-passed flags have nothing to do with it. Nothing of this affects slob. Link: http://lkml.kernel.org/r/20180927171502.226522-1-dvyukov@gmail.com Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Reported-by: syzbot+87829a10073277282ad1@syzkaller.appspotmail.com Reported-by: syzbot+ef4e8fc3a06e9019bb40@syzkaller.appspotmail.com Reported-by: syzbot+6e438f4036df52cbb863@syzkaller.appspotmail.com Reported-by: syzbot+8574471d8734457d98aa@syzkaller.appspotmail.com Reported-by: syzbot+af1504df0807a083dbd9@syzkaller.appspotmail.com Acked-by: Christoph Lameter <cl@linux.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab_common.c')
-rw-r--r--mm/slab_common.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index fea3376f9816..3a7ac4f15194 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1027,18 +1027,18 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
{
unsigned int index;
- if (unlikely(size > KMALLOC_MAX_SIZE)) {
- WARN_ON_ONCE(!(flags & __GFP_NOWARN));
- return NULL;
- }
-
if (size <= 192) {
if (!size)
return ZERO_SIZE_PTR;
index = size_index[size_index_elem(size)];
- } else
+ } else {
+ if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
+ WARN_ON(1);
+ return NULL;
+ }
index = fls(size - 1);
+ }
#ifdef CONFIG_ZONE_DMA
if (unlikely((flags & GFP_DMA)))