From: Vlastimil Babka <vbabka@suse.cz>
To: Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: mmotm woes, mainly compaction
Date: Tue, 12 Apr 2016 10:03:47 +0200 [thread overview]
Message-ID: <570CABE3.4070404@suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.11.1604120005350.1832@eggly.anvils>
On 04/12/2016 09:18 AM, Hugh Dickins wrote:
> 2. Fix crash in get_pfnblock_flags_mask() from suitable_migration_target()
> from isolate_freepages(): there's a case when that "block_start_pfn -=
> pageblock_nr_pages" loop can pass through 0 and end up trying to access
> a pageblock before the start of the mem_map[]. (I have not worked out
> why this never hit me before 4.6-rc2-mm1, it looks much older.)
This is actually my fresh mmotm bug, thanks for catching that!
Fix for:
mm-compaction-wrap-calculating-first-and-last-pfn-of-pageblock.patch
----8<----
WARNING: multiple messages have this Message-ID (diff)
From: Vlastimil Babka <vbabka@suse.cz>
To: Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: mmotm woes, mainly compaction
Date: Tue, 12 Apr 2016 10:03:47 +0200 [thread overview]
Message-ID: <570CABE3.4070404@suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.11.1604120005350.1832@eggly.anvils>
On 04/12/2016 09:18 AM, Hugh Dickins wrote:
> 2. Fix crash in get_pfnblock_flags_mask() from suitable_migration_target()
> from isolate_freepages(): there's a case when that "block_start_pfn -=
> pageblock_nr_pages" loop can pass through 0 and end up trying to access
> a pageblock before the start of the mem_map[]. (I have not worked out
> why this never hit me before 4.6-rc2-mm1, it looks much older.)
This is actually my fresh mmotm bug, thanks for catching that!
Fix for:
mm-compaction-wrap-calculating-first-and-last-pfn-of-pageblock.patch
----8<----
>From 45330dfb350d6b3bc72bcdaccc226bcc286e1236 Mon Sep 17 00:00:00 2001
From: Vlastimil Babka <vbabka@suse.cz>
Date: Tue, 12 Apr 2016 09:54:33 +0200
Subject: [PATCH] mm, compaction: fix crash in get_pfnblock_flags_mask() from
isolate_freepages():
In isolate_freepages(), low_pfn was mistakenly initialized to
pageblock_start_pfn() instead of pageblock_end_pfn(), creating a possible
underflow, as described by Hugh:
There's a case when that "block_start_pfn -= pageblock_nr_pages" loop can
pass through 0 and end up trying to access a pageblock before the start of
the mem_map[].
Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
mm/compaction.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/compaction.c b/mm/compaction.c
index 315e5d57e7e9..67f886ecd773 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1012,7 +1012,7 @@ static void isolate_freepages(struct compact_control *cc)
block_start_pfn = pageblock_start_pfn(cc->free_pfn);
block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
zone_end_pfn(zone));
- low_pfn = pageblock_start_pfn(cc->migrate_pfn);
+ low_pfn = pageblock_end_pfn(cc->migrate_pfn);
/*
* Isolate free pages until enough are available to migrate the
--
2.8.1
next prev parent reply other threads:[~2016-04-12 8:03 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-12 7:18 mmotm woes, mainly compaction Hugh Dickins
2016-04-12 7:18 ` Hugh Dickins
2016-04-12 8:03 ` Vlastimil Babka [this message]
2016-04-12 8:03 ` Vlastimil Babka
2016-04-12 9:03 ` Vlastimil Babka
2016-04-12 9:03 ` Vlastimil Babka
2016-04-12 9:14 ` Vlastimil Babka
2016-04-12 9:14 ` Vlastimil Babka
2016-04-12 9:31 ` Vlastimil Babka
2016-04-12 9:31 ` Vlastimil Babka
2016-04-12 9:38 ` Vlastimil Babka
2016-04-12 9:38 ` Vlastimil Babka
2016-04-12 12:10 ` Michal Hocko
2016-04-12 12:10 ` Michal Hocko
2016-04-12 14:51 ` Michal Hocko
2016-04-12 14:51 ` Michal Hocko
2016-04-14 20:15 ` Hugh Dickins
2016-04-14 20:15 ` Hugh Dickins
2016-04-14 23:24 ` Vlastimil Babka
2016-04-14 23:24 ` Vlastimil Babka
2016-04-15 1:00 ` Hugh Dickins
2016-04-15 1:00 ` Hugh Dickins
2016-04-18 19:14 ` Vlastimil Babka
2016-04-18 19:14 ` Vlastimil Babka
2016-04-15 8:42 ` Michal Hocko
2016-04-15 8:42 ` Michal Hocko
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