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Commit 8bf8fcb0 authored by Sebastian Ott's avatar Sebastian Ott Committed by Linus Torvalds
Browse files

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: default avatarSebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 02a8efed

mm/mempool.c

+2 −0
Original line number Diff line number Diff line
@@ -192,6 +192,7 @@ EXPORT_SYMBOL(mempool_resize); 
 * returns NULL. Note that due to preallocation, this function

 * *never* fails when called from process contexts. (it might

 * fail if called from an IRQ context.)

 * Note: using __GFP_ZERO is not supported.

 */

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;

	gfp_t gfp_temp;



	VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);

	might_sleep_if(gfp_mask & __GFP_WAIT);



	gfp_mask |= __GFP_NOMEMALLOC;	/* don't allocate emergency reserves */