linux-kernel - Re: [PATCH v2] mm/compaction: abort search if isolation fails

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Message-ID: <20190321171453.GE3189@techsingularity.net>
Date:   Thu, 21 Mar 2019 17:14:53 +0000
From:   Mel Gorman <mgorman@...hsingularity.net>
To:     Qian Cai <cai@....pw>
Cc:     akpm@...ux-foundation.org, daniel.m.jordan@...cle.com,
        mikhail.v.gavrilov@...il.com, vbabka@...e.cz,
        pasha.tatashin@...een.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/compaction: abort search if isolation fails

On Wed, Mar 20, 2019 at 03:26:48PM -0400, Qian Cai wrote:
> Running LTP oom01 in a tight loop or memory stress testing put the
> system in a low-memory situation could triggers random memory
> corruption like page flag corruption below due to in
> fast_isolate_freepages(), if isolation fails, next_search_order() does
> not abort the search immediately could lead to improper accesses.
> 
> UBSAN: Undefined behaviour in ./include/linux/mm.h:1195:50
> index 7 is out of range for type 'zone [5]'
> Call Trace:
>  dump_stack+0x62/0x9a
>  ubsan_epilogue+0xd/0x7f
>  __ubsan_handle_out_of_bounds+0x14d/0x192
>  __isolate_free_page+0x52c/0x600
>  compaction_alloc+0x886/0x25f0
>  unmap_and_move+0x37/0x1e70
>  migrate_pages+0x2ca/0xb20
>  compact_zone+0x19cb/0x3620
>  kcompactd_do_work+0x2df/0x680
>  kcompactd+0x1d8/0x6c0
>  kthread+0x32c/0x3f0
>  ret_from_fork+0x35/0x40
> ------------[ cut here ]------------
> kernel BUG at mm/page_alloc.c:3124!
> invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN PTI
> RIP: 0010:__isolate_free_page+0x464/0x600
> RSP: 0000:ffff888b9e1af848 EFLAGS: 00010007
> RAX: 0000000030000000 RBX: ffff888c39fcf0f8 RCX: 0000000000000000
> RDX: 1ffff111873f9e25 RSI: 0000000000000004 RDI: ffffed1173c35ef6
> RBP: ffff888b9e1af898 R08: fffffbfff4fc2461 R09: fffffbfff4fc2460
> R10: fffffbfff4fc2460 R11: ffffffffa7e12303 R12: 0000000000000008
> R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000007
> FS:  0000000000000000(0000) GS:ffff888ba8e80000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fc7abc00000 CR3: 0000000752416004 CR4: 00000000001606a0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  compaction_alloc+0x886/0x25f0
>  unmap_and_move+0x37/0x1e70
>  migrate_pages+0x2ca/0xb20
>  compact_zone+0x19cb/0x3620
>  kcompactd_do_work+0x2df/0x680
>  kcompactd+0x1d8/0x6c0
>  kthread+0x32c/0x3f0
>  ret_from_fork+0x35/0x40
> 
> Fixes: dbe2d4e4f12e ("mm, compaction: round-robin the order while searching the free lists for a target")
> Signed-off-by: Qian Cai <cai@....pw>

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

-- 
Mel Gorman
SUSE Labs