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| author | Dmitry Vyukov <dvyukov@google.com> | 2018-10-27 01:03:12 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-10-27 02:25:19 +0300 |
| commit | 61448479a9f2c954cde0cfe778cb6bec5d0a748d (patch) | |
| tree | 4c549b9918e7652c7fe73701eef9a7c6f5555e08 /mm/slab.c | |
| parent | 0684e6526edfb4debf0a0a884834bb1a104085dc (diff) | |
| download | linux-61448479a9f2c954cde0cfe778cb6bec5d0a748d.tar.xz | |
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.c')
| -rw-r--r-- | mm/slab.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/slab.c b/mm/slab.c index aa76a70e087e..d73c7a4820a4 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -3675,6 +3675,8 @@ __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) struct kmem_cache *cachep; void *ret; + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) + return NULL; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; @@ -3710,6 +3712,8 @@ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags, struct kmem_cache *cachep; void *ret; + if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) + return NULL; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; |