From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 97AA39000C2 for ; Tue, 26 Apr 2011 05:50:02 -0400 (EDT) Date: Tue, 26 Apr 2011 19:49:47 +1000 From: NeilBrown Subject: Re: [PATCH 03/13] mm: Introduce __GFP_MEMALLOC to allow access to emergency reserves Message-ID: <20110426194947.764e048a@notabene.brown> In-Reply-To: <1303803414-5937-4-git-send-email-mgorman@suse.de> References: <1303803414-5937-1-git-send-email-mgorman@suse.de> <1303803414-5937-4-git-send-email-mgorman@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Linux-MM , Linux-Netdev , LKML , David Miller , Peter Zijlstra On Tue, 26 Apr 2011 08:36:44 +0100 Mel Gorman wrote: > __GFP_MEMALLOC will allow the allocation to disregard the watermarks, > much like PF_MEMALLOC. It allows one to pass along the memalloc state in > object related allocation flags as opposed to task related flags, such > as sk->sk_allocation. This removes the need for ALLOC_PFMEMALLOC as > callers using __GFP_MEMALLOC can get the ALLOC_NO_WATERMARK flag which > is now enough to identify allocations related to page reclaim. > > Signed-off-by: Peter Zijlstra > Signed-off-by: Mel Gorman > --- > include/linux/gfp.h | 4 +++- > include/linux/mm_types.h | 2 +- > mm/page_alloc.c | 14 ++++++-------- > mm/slab.c | 2 +- > 4 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/include/linux/gfp.h b/include/linux/gfp.h > index bfb8f93..4e011e7 100644 > --- a/include/linux/gfp.h > +++ b/include/linux/gfp.h > @@ -23,6 +23,7 @@ struct vm_area_struct; > #define ___GFP_REPEAT 0x400u > #define ___GFP_NOFAIL 0x800u > #define ___GFP_NORETRY 0x1000u > +#define ___GFP_MEMALLOC 0x2000u > #define ___GFP_COMP 0x4000u > #define ___GFP_ZERO 0x8000u > #define ___GFP_NOMEMALLOC 0x10000u > @@ -75,6 +76,7 @@ struct vm_area_struct; > #define __GFP_REPEAT ((__force gfp_t)___GFP_REPEAT) /* See above */ > #define __GFP_NOFAIL ((__force gfp_t)___GFP_NOFAIL) /* See above */ > #define __GFP_NORETRY ((__force gfp_t)___GFP_NORETRY) /* See above */ > +#define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC)/* Allow access to emergency reserves */ > #define __GFP_COMP ((__force gfp_t)___GFP_COMP) /* Add compound page metadata */ > #define __GFP_ZERO ((__force gfp_t)___GFP_ZERO) /* Return zeroed page on success */ > #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) /* Don't use emergency reserves */ Having both "MEMALLOC" and "NOMEMALLOC" seems ... unfortunate. It appears that NOMEMALLOC over-rides MEMALLOC. It might be good to document this > +#define __GFP_MEMALLOC ((__force gfp_t)___GFP_MEMALLOC)/* Allow access to emergency reserves unless __GFP_NOMEMALLOC is set*/ > #define __GFP_NOMEMALLOC ((__force gfp_t)___GFP_NOMEMALLOC) /* Don't use emergency reserves Overrides __GFP_MEMALLOC */ I suspect that it is never valid to set both. So NOMEMALLOC is really NO_PF_MEMALLOC, but making that change is probably just noise. Maybe a WARN_ON((gfp_mask & __GFP_MEMALLOC) && (gfp_mask & __GFP_NOMEMALLOC)); might be wise? NeilBrown. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org