From: Rongwei Wang <rongwei.wang@linux.alibaba.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, song@kernel.org,
william.kucharski@oracle.com, hughd@google.com
Subject: Re: [PATCH v3 v3 2/2] mm, thp: bail out early in collapse_file for writeback page
Date: Wed, 6 Oct 2021 16:39:47 +0800 [thread overview]
Message-ID: <ad61320f-7903-997f-b468-8d260ea0ad66@linux.alibaba.com> (raw)
In-Reply-To: <YV0M9NHi6I4ULFe6@casper.infradead.org>
On 10/6/21 10:41 AM, Matthew Wilcox wrote:
> On Wed, Oct 06, 2021 at 10:18:37AM +0800, Rongwei Wang wrote:
>> Currently collapse_file does not explicitly check PG_writeback, instead,
>> page_has_private and try_to_release_page are used to filter writeback
>> pages. This does not work for xfs with blocksize equal to or larger
>> than pagesize, because in such case xfs has no page->private.
>>
>> This makes collapse_file bail out early for writeback page. Otherwise,
>> xfs end_page_writeback will panic as follows.
>
> Could you cut the timestamps out? They don't add any value.
OK, no problem!
>
>> [ 6411.448211] page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:ffff0003f88c86a8 index:0x0 pfn:0x84ef32
>> [ 6411.448304] aops:xfs_address_space_operations [xfs] ino:30000b7 dentry name:"libtest.so"
>> [ 6411.448312] flags: 0x57fffe0000008027(locked|referenced|uptodate|active|writeback)
>> [ 6411.448317] raw: 57fffe0000008027 ffff80001b48bc28 ffff80001b48bc28 ffff0003f88c86a8
>> [ 6411.448321] raw: 0000000000000000 0000000000000000 00000000ffffffff ffff0000c3e9a000
>> [ 6411.448324] page dumped because: VM_BUG_ON_PAGE(((unsigned int) page_ref_count(page) + 127u <= 127u))
>> [ 6411.448327] page->mem_cgroup:ffff0000c3e9a000
>> [ 6411.448340] ------------[ cut here ]------------
>> [ 6411.448343] kernel BUG at include/linux/mm.h:1212!
>> [ 6411.449288] Internal error: Oops - BUG: 0 [#1] SMP
>> [ 6411.449786] Modules linked in:
>> [ 6411.449790] BUG: Bad page state in process khugepaged pfn:84ef32
>> [ 6411.450143] xfs(E)
>> [ 6411.450459] page:fffffe00201bcc80 refcount:0 mapcount:0 mapping:0 index:0x0 pfn:0x84ef32
>> [ 6411.451361] libcrc32c(E) rfkill(E) aes_ce_blk(E) crypto_simd(E) ...
>> [ 6411.451387] CPU: 25 PID: 0 Comm: swapper/25 Kdump: loaded Tainted: ...
>> [ 6411.451389] pstate: 60400005 (nZCv daif +PAN -UAO -TCO BTYPE=--)
>> [ 6411.451393] pc : end_page_writeback+0x1c0/0x214
>> [ 6411.451394] lr : end_page_writeback+0x1c0/0x214
>> [ 6411.451395] sp : ffff800011ce3cc0
>> [ 6411.451396] x29: ffff800011ce3cc0 x28: 0000000000000000
>> [ 6411.451398] x27: ffff000c04608040 x26: 0000000000000000
>> [ 6411.451399] x25: ffff000c04608040 x24: 0000000000001000
>> [ 6411.451401] x23: ffff0003f88c8530 x22: 0000000000001000
>> [ 6411.451403] x21: ffff0003f88c8530 x20: 0000000000000000
>> [ 6411.451404] x19: fffffe00201bcc80 x18: 0000000000000030
>> [ 6411.451406] x17: 0000000000000000 x16: 0000000000000000
>> [ 6411.451407] x15: ffff000c018f9760 x14: ffffffffffffffff
>> [ 6411.451409] x13: ffff8000119d72b0 x12: ffff8000119d6ee3
>> [ 6411.451410] x11: ffff8000117b69b8 x10: 00000000ffff8000
>> [ 6411.451412] x9 : ffff800010617534 x8 : 0000000000000000
>> [ 6411.451413] x7 : ffff8000114f69b8 x6 : 000000000000000f
>> [ 6411.451415] x5 : 0000000000000000 x4 : 0000000000000000
>> [ 6411.451416] x3 : 0000000000000400 x2 : 0000000000000000
>> [ 6411.451418] x1 : 0000000000000000 x0 : 0000000000000000
>> [ 6411.451420] Call trace:
>> [ 6411.451421] end_page_writeback+0x1c0/0x214
>> [ 6411.451424] iomap_finish_page_writeback+0x13c/0x204
>> [ 6411.451425] iomap_finish_ioend+0xe8/0x19c
>> [ 6411.451426] iomap_writepage_end_bio+0x38/0x50
>> [ 6411.451427] bio_endio+0x168/0x1ec
>> [ 6411.451430] blk_update_request+0x278/0x3f0
>> [ 6411.451432] blk_mq_end_request+0x34/0x15c
>> [ 6411.451435] virtblk_request_done+0x38/0x74 [virtio_blk]
>> [ 6411.451437] blk_done_softirq+0xc4/0x110
>> [ 6411.451439] __do_softirq+0x128/0x38c
>> [ 6411.451441] __irq_exit_rcu+0x118/0x150
>> [ 6411.451442] irq_exit+0x1c/0x30
>> [ 6411.451445] __handle_domain_irq+0x8c/0xf0
>> [ 6411.451446] gic_handle_irq+0x84/0x108
>> [ 6411.451447] el1_irq+0xcc/0x180
>> [ 6411.451448] arch_cpu_idle+0x18/0x40
>> [ 6411.451450] default_idle_call+0x4c/0x1a0
>> [ 6411.451453] cpuidle_idle_call+0x168/0x1e0
>> [ 6411.451454] do_idle+0xb4/0x104
>> [ 6411.451455] cpu_startup_entry+0x30/0x9c
>> [ 6411.451458] secondary_start_kernel+0x104/0x180
>> [ 6411.451460] Code: d4210000 b0006161 910c8021 94013f4d (d4210000)
>> [ 6411.451462] ---[ end trace 4a88c6a074082f8c ]---
>> [ 6411.451464] Kernel panic - not syncing: Oops - BUG: Fatal exception in interrupt
>>
>> Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs")
>> Suggested-by: Yang Shi <shy828301@gmail.com>
>> Signed-off-by: Xu Yu <xuyu@linux.alibaba.com>
>> Signed-off-by: Rongwei Wang <rongwei.wang@linux.alibaba.com>
>
> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
>
> Although I think the Fixes: line is wrong. This bug goes all the
> way back to 99cb0dbd47a1.
In fact, I understand it this way: the 99cb0dbd47a1 only introduce
file-backed THP for VMA with MAP_DENYWRITE, denying write directly not
to truncate pagecache when it is opened. And eb6ecbed0aa2 will to
truncate pagecache when DSO is opened by a writer, then will trigger ...
It seems 'Fixes: eb6ecbed0aa2' is more reasonable.
>
next prev parent reply other threads:[~2021-10-06 8:39 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-06 12:11 [PATCH 0/2] mm, thp: fix file-backed THP race in collapse_file Rongwei Wang
2021-09-06 12:11 ` [PATCH 1/2] mm, thp: check page mapping when truncating page cache Rongwei Wang
2021-09-07 2:49 ` Yu Xu
2021-09-07 18:08 ` Yang Shi
2021-09-08 2:35 ` Rongwei Wang
2021-09-08 21:48 ` Yang Shi
2021-09-09 1:25 ` Rongwei Wang
2021-09-13 14:49 ` [mm, thp] 20753096b6: BUG:unable_to_handle_page_fault_for_address kernel test robot
2021-09-06 12:12 ` [PATCH 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-09-07 16:56 ` Yang Shi
2021-09-08 2:16 ` Rongwei Wang
2021-09-08 21:51 ` Yang Shi
2021-09-09 1:33 ` Rongwei Wang
2021-09-22 7:06 ` [PATCH v2 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-09-22 7:06 ` [PATCH v2 1/2] mm, thp: check page mapping when truncating page cache Rongwei Wang
2021-09-22 11:37 ` Matthew Wilcox
2021-09-22 17:04 ` Rongwei Wang
2021-09-24 2:43 ` Andrew Morton
2021-09-24 3:08 ` Yang Shi
2021-09-24 3:35 ` Rongwei Wang
2021-09-24 7:12 ` Rongwei Wang
2021-09-27 22:24 ` Song Liu
2021-09-28 12:06 ` Matthew Wilcox
2021-09-28 16:59 ` Song Liu
2021-09-28 16:20 ` Rongwei Wang
2021-09-29 7:14 ` Song Liu
2021-09-29 7:50 ` Rongwei Wang
2021-09-29 16:59 ` Song Liu
2021-09-29 17:55 ` Matthew Wilcox
2021-09-29 23:41 ` Song Liu
2021-09-30 0:00 ` Matthew Wilcox
2021-09-30 0:41 ` Song Liu
2021-09-30 2:14 ` Rongwei Wang
2021-10-04 17:26 ` Rongwei Wang
2021-10-04 19:05 ` Matthew Wilcox
2021-10-05 1:58 ` Rongwei Wang
2021-10-04 20:26 ` Song Liu
2021-10-05 2:58 ` Hugh Dickins
2021-10-05 3:07 ` Matthew Wilcox
2021-10-05 9:03 ` Rongwei Wang
2021-09-30 1:54 ` Rongwei Wang
2021-09-30 3:26 ` Song Liu
2021-09-30 5:24 ` Hugh Dickins
2021-09-30 15:28 ` Matthew Wilcox
2021-09-30 16:49 ` Hugh Dickins
2021-09-30 17:39 ` Yang Shi
2021-10-02 17:08 ` Matthew Wilcox
2021-10-04 18:28 ` Yang Shi
2021-10-04 19:31 ` Matthew Wilcox
2021-10-05 2:26 ` Hugh Dickins
2021-10-02 2:22 ` Rongwei Wang
2021-09-22 7:06 ` [PATCH v2 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-06 2:18 ` [PATCH v3 v3 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-10-06 2:18 ` [PATCH v3 v3 1/2] mm, thp: lock filemap when truncating page cache Rongwei Wang
2021-10-06 2:18 ` [PATCH v3 v3 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-06 2:41 ` Matthew Wilcox
2021-10-06 8:39 ` Rongwei Wang [this message]
2021-10-06 17:58 ` Yang Shi
2021-10-11 2:22 ` [PATCH v4 0/2] mm, thp: fix file-backed THP race in collapse_file and truncate pagecache Rongwei Wang
2021-10-11 2:22 ` [PATCH v4 1/2] mm, thp: lock filemap when truncating page cache Rongwei Wang
2021-10-13 7:55 ` Rongwei Wang
2021-10-11 2:22 ` [PATCH v4 2/2] mm, thp: bail out early in collapse_file for writeback page Rongwei Wang
2021-10-11 3:08 ` Matthew Wilcox
2021-10-11 3:22 ` Rongwei Wang
2021-10-11 5:08 ` [PATCH v4 RESEND " Rongwei Wang
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