Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752762Ab2KLLhh (ORCPT ); Mon, 12 Nov 2012 06:37:37 -0500 Received: from cantor2.suse.de ([195.135.220.15]:59076 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752467Ab2KLLhg (ORCPT ); Mon, 12 Nov 2012 06:37:36 -0500 Date: Mon, 12 Nov 2012 11:37:31 +0000 From: Mel Gorman To: Zdenek Kabelac Cc: Seth Jennings , Jiri Slaby , Valdis.Kletnieks@vt.edu, Jiri Slaby , linux-mm@kvack.org, LKML , Andrew Morton , Rik van Riel , Robert Jennings Subject: [PATCH] Revert "mm: remove __GFP_NO_KSWAPD" Message-ID: <20121112113731.GS8218@suse.de> References: <20121012135726.GY29125@suse.de> <507BDD45.1070705@suse.cz> <20121015110937.GE29125@suse.de> <5093A3F4.8090108@redhat.com> <5093A631.5020209@suse.cz> <509422C3.1000803@suse.cz> <509C84ED.8090605@linux.vnet.ibm.com> <509CB9D1.6060704@redhat.com> <20121109090635.GG8218@suse.de> <509F6C2A.9060502@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <509F6C2A.9060502@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6495 Lines: 148 With "mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures" reverted, Zdenek Kabelac reported the following Hmm, so it's just took longer to hit the problem and observe kswapd0 spinning on my CPU again - it's not as endless like before - but still it easily eats minutes - it helps to turn off Firefox or TB (memory hungry apps) so kswapd0 stops soon - and restart those apps again. (And I still have like >1GB of cached memory) kswapd0 R running task 0 30 2 0x00000000 ffff8801331efae8 0000000000000082 0000000000000018 0000000000000246 ffff880135b9a340 ffff8801331effd8 ffff8801331effd8 ffff8801331effd8 ffff880055dfa340 ffff880135b9a340 00000000331efad8 ffff8801331ee000 Call Trace: [] preempt_schedule+0x42/0x60 [] _raw_spin_unlock+0x55/0x60 [] put_super+0x31/0x40 [] drop_super+0x22/0x30 [] prune_super+0x149/0x1b0 [] shrink_slab+0xba/0x510 The sysrq+m indicates the system has no swap so it'll never reclaim anonymous pages as part of reclaim/compaction. That is one part of the problem but not the root cause as file-backed pages could also be reclaimed. The likely underlying problem is that kswapd is woken up or kept awake for each THP allocation request in the page allocator slow path. If compaction fails for the requesting process then compaction will be deferred for a time and direct reclaim is avoided. However, if there are a storm of THP requests that are simply rejected, it will still be the the case that kswapd is awake for a prolonged period of time as pgdat->kswapd_max_order is updated each time. This is noticed by the main kswapd() loop and it will not call kswapd_try_to_sleep(). Instead it will loopp, shrinking a small number of pages and calling shrink_slab() on each iteration. The temptation is to supply a patch that checks if kswapd was woken for THP and if so ignore pgdat->kswapd_max_order but it'll be a hack and not backed up by proper testing. As 3.7 is very close to release and this is not a bug we should release with, a safer path is to revert "mm: remove __GFP_NO_KSWAPD" for now and revisit it with the view to ironing out the balance_pgdat() logic in general. Signed-off-by: Mel Gorman --- drivers/mtd/mtdcore.c | 6 ++++-- include/linux/gfp.h | 5 ++++- include/trace/events/gfpflags.h | 1 + mm/page_alloc.c | 7 ++++--- 4 files changed, 13 insertions(+), 6 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 374c46d..ec794a7 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -1077,7 +1077,8 @@ EXPORT_SYMBOL_GPL(mtd_writev); * until the request succeeds or until the allocation size falls below * the system page size. This attempts to make sure it does not adversely * impact system performance, so when allocating more than one page, we - * ask the memory allocator to avoid re-trying. + * ask the memory allocator to avoid re-trying, swapping, writing back + * or performing I/O. * * Note, this function also makes sure that the allocated buffer is aligned to * the MTD device's min. I/O unit, i.e. the "mtd->writesize" value. @@ -1091,7 +1092,8 @@ EXPORT_SYMBOL_GPL(mtd_writev); */ void *mtd_kmalloc_up_to(const struct mtd_info *mtd, size_t *size) { - gfp_t flags = __GFP_NOWARN | __GFP_WAIT | __GFP_NORETRY; + gfp_t flags = __GFP_NOWARN | __GFP_WAIT | + __GFP_NORETRY | __GFP_NO_KSWAPD; size_t min_alloc = max_t(size_t, mtd->writesize, PAGE_SIZE); void *kbuf; diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 02c1c971..d0a7967 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -31,6 +31,7 @@ struct vm_area_struct; #define ___GFP_THISNODE 0x40000u #define ___GFP_RECLAIMABLE 0x80000u #define ___GFP_NOTRACK 0x200000u +#define ___GFP_NO_KSWAPD 0x400000u #define ___GFP_OTHER_NODE 0x800000u #define ___GFP_WRITE 0x1000000u @@ -85,6 +86,7 @@ struct vm_area_struct; #define __GFP_RECLAIMABLE ((__force gfp_t)___GFP_RECLAIMABLE) /* Page is reclaimable */ #define __GFP_NOTRACK ((__force gfp_t)___GFP_NOTRACK) /* Don't track with kmemcheck */ +#define __GFP_NO_KSWAPD ((__force gfp_t)___GFP_NO_KSWAPD) #define __GFP_OTHER_NODE ((__force gfp_t)___GFP_OTHER_NODE) /* On behalf of other node */ #define __GFP_WRITE ((__force gfp_t)___GFP_WRITE) /* Allocator intends to dirty page */ @@ -114,7 +116,8 @@ struct vm_area_struct; __GFP_MOVABLE) #define GFP_IOFS (__GFP_IO | __GFP_FS) #define GFP_TRANSHUGE (GFP_HIGHUSER_MOVABLE | __GFP_COMP | \ - __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN) + __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_NOWARN | \ + __GFP_NO_KSWAPD) #ifdef CONFIG_NUMA #define GFP_THISNODE (__GFP_THISNODE | __GFP_NOWARN | __GFP_NORETRY) diff --git a/include/trace/events/gfpflags.h b/include/trace/events/gfpflags.h index 9391706..d6fd8e5 100644 --- a/include/trace/events/gfpflags.h +++ b/include/trace/events/gfpflags.h @@ -36,6 +36,7 @@ {(unsigned long)__GFP_RECLAIMABLE, "GFP_RECLAIMABLE"}, \ {(unsigned long)__GFP_MOVABLE, "GFP_MOVABLE"}, \ {(unsigned long)__GFP_NOTRACK, "GFP_NOTRACK"}, \ + {(unsigned long)__GFP_NO_KSWAPD, "GFP_NO_KSWAPD"}, \ {(unsigned long)__GFP_OTHER_NODE, "GFP_OTHER_NODE"} \ ) : "GFP_NOWAIT" diff --git a/mm/page_alloc.c b/mm/page_alloc.c index bb90971..7228260 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2416,8 +2416,9 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, goto nopage; restart: - wake_all_kswapd(order, zonelist, high_zoneidx, - zone_idx(preferred_zone)); + if (!(gfp_mask & __GFP_NO_KSWAPD)) + wake_all_kswapd(order, zonelist, high_zoneidx, + zone_idx(preferred_zone)); /* * OK, we're below the kswapd watermark and have kicked background @@ -2494,7 +2495,7 @@ rebalance: * system then fail the allocation instead of entering direct reclaim. */ if ((deferred_compaction || contended_compaction) && - (gfp_mask & (__GFP_MOVABLE|__GFP_REPEAT)) == __GFP_MOVABLE) + (gfp_mask & __GFP_NO_KSWAPD)) goto nopage; /* Try direct reclaim and then allocating */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/