linux-kernel - [patch] mm, page_alloc: allow __GFP_NOFAIL to allocate below watermarks after reclaim

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 9 Dec 2013 14:03:45 -0800 (PST)
From:	David Rientjes <rientjes@...gle.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...e.cz>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [patch] mm, page_alloc: allow __GFP_NOFAIL to allocate below watermarks
 after reclaim

If direct reclaim has failed to free memory, __GFP_NOFAIL allocations
can potentially loop forever in the page allocator.  In this case, it's
better to give them the ability to access below watermarks so that they
may allocate similar to the same privilege given to GFP_ATOMIC
allocations.

We're careful to ensure this is only done after direct reclaim has had
the chance to free memory, however.

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 mm/page_alloc.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2629,6 +2629,11 @@ rebalance:
 						pages_reclaimed)) {
 		/* Wait for some write requests to complete then retry */
 		wait_iff_congested(preferred_zone, BLK_RW_ASYNC, HZ/50);
+
+		/* Allocations that cannot fail must allocate from somewhere */
+		if (gfp_mask & __GFP_NOFAIL)
+			alloc_flags |= ALLOC_HARDER;
+
 		goto rebalance;
 	} else {
 		/*
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/