From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Marcin Wojtas <mw@semihalf.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm, slaub: Add __GFP_ATOMIC to the GFP reclaim mask
Date: Fri, 10 Jun 2016 12:12:45 +0200 [thread overview]
Message-ID: <575A929D.3070601@suse.cz> (raw)
In-Reply-To: <20160610093832.GK2527@techsingularity.net>
On 06/10/2016 11:38 AM, Mel Gorman wrote:
> Commit d0164adc89f6 ("mm, page_alloc: distinguish between being unable to
> sleep, unwilling to sleep and avoiding waking kswapd") modified __GFP_WAIT
> to explicitly identify the difference between atomic callers and those that
> were unwilling to sleep. Later the definition was removed entirely.
>
> The GFP_RECLAIM_MASK is the set of flags that affect watermark checking
> and reclaim behaviour but __GFP_ATOMIC was never added. Without it, atomic
> users of the slab allocator strip the __GFP_ATOMIC flag and cannot access
> the page allocator atomic reserves. This patch addresses the problem.
>
> The user-visible impact depends on the workload but potentially atomic
> allocations unnecessarily fail without this path.
>
> Cc: <stable@vger.kernel.org> # 4.4+
> Reported-by: Marcin Wojtas <mw@semihalf.com>
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/internal.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index a37e5b6f9d25..2524ec880e24 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -24,7 +24,8 @@
> */
> #define GFP_RECLAIM_MASK (__GFP_RECLAIM|__GFP_HIGH|__GFP_IO|__GFP_FS|\
> __GFP_NOWARN|__GFP_REPEAT|__GFP_NOFAIL|\
> - __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC)
> + __GFP_NORETRY|__GFP_MEMALLOC|__GFP_NOMEMALLOC|\
> + __GFP_ATOMIC)
>
> /* The GFP flags allowed during early boot */
> #define GFP_BOOT_MASK (__GFP_BITS_MASK & ~(__GFP_RECLAIM|__GFP_IO|__GFP_FS))
>
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next prev parent reply other threads:[~2016-06-10 10:12 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-10 9:38 [PATCH] mm, slaub: Add __GFP_ATOMIC to the GFP reclaim mask Mel Gorman
2016-06-10 10:12 ` Vlastimil Babka [this message]
2016-06-14 6:36 ` Michal Hocko
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