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mm/mempool: warn about __GFP_ZERO usage 

Memory obtained via mempool_alloc is not always zeroed even when
called with __GFP_ZERO. Add a note and VM_BUG_ON statement to make
that clear.

[akpm@linux-foundation.org: use VM_WARN_ON_ONCE]
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Sebastian Ott 2014-06-04 16:07:00 -07:00 committed by Linus Torvalds
parent 02a8efeda8
commit 8bf8fcb076
1 changed files with 2 additions and 0 deletions
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2
mm/mempool.c
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@ -192,6 +192,7 @@ EXPORT_SYMBOL(mempool_resize);
* returns NULL. Note that due to preallocation, this function * returns NULL. Note that due to preallocation, this function
* *never* fails when called from process contexts. (it might * *never* fails when called from process contexts. (it might
* fail if called from an IRQ context.) * fail if called from an IRQ context.)
* Note: using __GFP_ZERO is not supported.
*/ */
void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask) void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
{ {
@ -200,6 +201,7 @@ void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
wait_queue_t wait; wait_queue_t wait;
gfp_t gfp_temp; gfp_t gfp_temp;
VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
might_sleep_if(gfp_mask & __GFP_WAIT); might_sleep_if(gfp_mask & __GFP_WAIT);
gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */ gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */