On Mon, 14 Apr 2014 19:23:34 +0200 (CEST) Sebastian Ott
<seb...@linux.vnet.ibm.com> wrote:
> 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.
>
> ..
>
> @@ -200,6 +201,7 @@ void * mempool_alloc(mempool_t *pool, gf
> wait_queue_t wait;
> gfp_t gfp_temp;
>
> + VM_BUG_ON(gfp_mask & __GFP_ZERO);
> might_sleep_if(gfp_mask & __GFP_WAIT);
>
> gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
hm, BUG is a bit harsh. How about
--- a/mm/mempool.c~mm-mempool-warn-about-__gfp_zero-usage-fix
+++ a/mm/mempool.c
@@ -201,7 +201,9 @@ void * mempool_alloc(mempool_t *pool, gf
wait_queue_t wait;
gfp_t gfp_temp;
- VM_BUG_ON(gfp_mask & __GFP_ZERO);
+#ifdef CONFIG_DEBUG_VM
+ WARN_ON_ONCE(gfp_mask & __GFP_ZERO); /* Where's VM_WARN_ON_ONCE()? */
+#endif
might_sleep_if(gfp_mask & __GFP_WAIT);
gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
?
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