From: Andrew Morton <akpm@linux-foundation.org>
To: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/mempool: warn about __GFP_ZERO usage
Date: Wed, 16 Apr 2014 14:15:56 -0700 [thread overview]
Message-ID: <20140416141556.d50eef60d955d724ba1b02de@linux-foundation.org> (raw)
In-Reply-To: <alpine.LFD.2.11.1404141918170.1561@denkbrett>
On Mon, 14 Apr 2014 19:23:34 +0200 (CEST) Sebastian Ott <sebott@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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next prev parent reply other threads:[~2014-04-16 21:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-14 17:23 [PATCH] mm/mempool: warn about __GFP_ZERO usage Sebastian Ott
2014-04-16 21:15 ` Andrew Morton [this message]
2014-04-16 21:22 ` Andrew Morton
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