linux-kernel - [RFC][PATCH 1/6] mm: Introduce __GFP_NO_OOM

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

Date:	Sun, 10 May 2009 15:50:08 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>, Pavel Machek <pavel@....cz>,
	Nigel Cunningham <nigel@...onice.net>,
	David Rientjes <rientjes@...gle.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: [RFC][PATCH 1/6] mm: Introduce __GFP_NO_OOM_KILL

From: Andrew Morton <akpm@...ux-foundation.org>

> > Remind me: why can't we just allocate N pages at suspend-time?
> 
> We need half of memory free. The reason we can't "just allocate" is
> probably OOM killer; but my memories are quite weak :-(.

hm.  You'd think that with our splendid range of __GFP_foo falgs, there
would be some combo which would suit this requirement but I can't
immediately spot one.

We can always add another I guess.  Something like...

[rjw: fixed white space, added comment in page_alloc.c]

Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 include/linux/gfp.h |    3 ++-
 mm/page_alloc.c     |    8 ++++++--
 2 files changed, 8 insertions(+), 3 deletions(-)

Index: linux-2.6/mm/page_alloc.c
===================================================================
--- linux-2.6.orig/mm/page_alloc.c
+++ linux-2.6/mm/page_alloc.c
@@ -1619,8 +1619,12 @@ nofail_alloc:
 			goto got_pg;
 		}
 
-		/* The OOM killer will not help higher order allocs so fail */
-		if (order > PAGE_ALLOC_COSTLY_ORDER) {
+		/*
+		 * The OOM killer will not help higher order allocs so fail.
+		 * Also fail if the caller doesn't want the OOM killer to run.
+		 */
+		if (order > PAGE_ALLOC_COSTLY_ORDER
+				|| (gfp_mask & __GFP_NO_OOM_KILL)) {
 			clear_zonelist_oom(zonelist, gfp_mask);
 			goto nopage;
 		}
Index: linux-2.6/include/linux/gfp.h
===================================================================
--- linux-2.6.orig/include/linux/gfp.h
+++ linux-2.6/include/linux/gfp.h
@@ -51,8 +51,9 @@ struct vm_area_struct;
 #define __GFP_THISNODE	((__force gfp_t)0x40000u)/* No fallback, no policies */
 #define __GFP_RECLAIMABLE ((__force gfp_t)0x80000u) /* Page is reclaimable */
 #define __GFP_MOVABLE	((__force gfp_t)0x100000u)  /* Page is movable */
+#define __GFP_NO_OOM_KILL ((__force gfp_t)0x200000u)  /* Don't invoke out_of_memory() */
 
-#define __GFP_BITS_SHIFT 21	/* Room for 21 __GFP_FOO bits */
+#define __GFP_BITS_SHIFT 22	/* Number of __GFP_FOO bits */
 #define __GFP_BITS_MASK ((__force gfp_t)((1 << __GFP_BITS_SHIFT) - 1))
 
 /* This equals 0, but use constants in case they ever change */
--
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/