Re: [PATCH AUTOSEL 5.7 37/53] cifs: Fix double add page to memcg when cifs_readpages

Sasha Levin
2020-07-09T23:49:43Z

On Thu, Jul 02, 2020 at 09:08:45AM -0700, Pavel Shilovsky wrote:
>ср, 1 июл. 2020 г. в 18:35, Sasha Levin <sashal@kernel.org>:
>>
>> From: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
>>
>> [ Upstream commit 95a3d8f3af9b0d63b43f221b630beaab9739d13a ]
>>
>> When xfstests generic/451, there is an BUG at mm/memcontrol.c:
>> page:ffffea000560f2c0 refcount:2 mapcount:0 mapping:000000008544e0ea
>> index:0xf
>> mapping->aops:cifs_addr_ops dentry name:"tst-aio-dio-cycle-write.451"
>> flags: 0x2fffff80000001(locked)
>> raw: 002fffff80000001 ffffc90002023c50 ffffea0005280088 ffff88815cda0210
>> raw: 000000000000000f 0000000000000000 00000002ffffffff ffff88817287d000
>> page dumped because: VM_BUG_ON_PAGE(page->mem_cgroup)
>> page->mem_cgroup:ffff88817287d000
>> ------------[ cut here ]------------
>> kernel BUG at mm/memcontrol.c:2659!
>> invalid opcode: 0000 [#1] SMP
>> CPU: 2 PID: 2038 Comm: xfs_io Not tainted 5.8.0-rc1 #44
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_
>> 073836-buildvm-ppc64le-16.ppc.4
>> RIP: 0010:commit_charge+0x35/0x50
>> Code: 0d 48 83 05 54 b2 02 05 01 48 89 77 38 c3 48 c7
>> c6 78 4a ea ba 48 83 05 38 b2 02 05 01 e8 63 0d9
>> RSP: 0018:ffffc90002023a50 EFLAGS: 00010202
>> RAX: 0000000000000000 RBX: ffff88817287d000 RCX: 0000000000000000
>> RDX: 0000000000000000 RSI: ffff88817ac97ea0 RDI: ffff88817ac97ea0
>> RBP: ffffea000560f2c0 R08: 0000000000000203 R09: 0000000000000005
>> R10: 0000000000000030 R11: ffffc900020237a8 R12: 0000000000000000
>> R13: 0000000000000001 R14: 0000000000000001 R15: ffff88815a1272c0
>> FS: 00007f5071ab0800(0000) GS:ffff88817ac80000(0000) knlGS:0000000000000000
>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 000055efcd5ca000 CR3: 000000015d312000 CR4: 00000000000006e0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>> mem_cgroup_charge+0x166/0x4f0
>> __add_to_page_cache_locked+0x4a9/0x710
>> add_to_page_cache_locked+0x15/0x20
>> cifs_readpages+0x217/0x1270
>> read_pages+0x29a/0x670
>> page_cache_readahead_unbounded+0x24f/0x390
>> __do_page_cache_readahead+0x3f/0x60
>> ondemand_readahead+0x1f1/0x470
>> page_cache_async_readahead+0x14c/0x170
>> generic_file_buffered_read+0x5df/0x1100
>> generic_file_read_iter+0x10c/0x1d0
>> cifs_strict_readv+0x139/0x170
>> new_sync_read+0x164/0x250
>> __vfs_read+0x39/0x60
>> vfs_read+0xb5/0x1e0
>> ksys_pread64+0x85/0xf0
>> __x64_sys_pread64+0x22/0x30
>> do_syscall_64+0x69/0x150
>> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x7f5071fcb1af
>> Code: Bad RIP value.
>> RSP: 002b:00007ffde2cdb8e0 EFLAGS: 00000293 ORIG_RAX: 0000000000000011
>> RAX: ffffffffffffffda RBX: 00007ffde2cdb990 RCX: 00007f5071fcb1af
>> RDX: 0000000000001000 RSI: 000055efcd5ca000 RDI: 0000000000000003
>> RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000001000 R11: 0000000000000293 R12: 0000000000000001
>> R13: 000000000009f000 R14: 0000000000000000 R15: 0000000000001000
>> Modules linked in:
>> ---[ end trace 725fa14a3e1af65c ]---
>>
>> Since commit 3fea5a499d57 ("mm: memcontrol: convert page cache to a new
>> mem_cgroup_charge() API") not cancel the page charge, the pages maybe
>> double add to pagecache:
>> thread1 | thread2
>> cifs_readpages
>> readpages_get_pages
>> add_to_page_cache_locked(head,index=n)=0
>> | readpages_get_pages
>> | add_to_page_cache_locked(head,index=n+1)=0
>> add_to_page_cache_locked(head, index=n+1)=-EEXIST
>> then, will next loop with list head page's
>> index=n+1 and the page->mapping not NULL
>> readpages_get_pages
>> add_to_page_cache_locked(head, index=n+1)
>> commit_charge
>> VM_BUG_ON_PAGE
>>
>> So, we should not do the next loop when any page add to page cache
>> failed.
>>
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Zhang Xiaoxu <zhangxiaoxu5@huawei.com>
>> Signed-off-by: Steve French <stfrench@microsoft.com>
>> Acked-by: Ronnie Sahlberg <lsahlber@redhat.com>
>> Signed-off-by: Sasha Levin <sashal@kernel.org>
>
>Hi Sasha,
>
>The patch description mentions the commit 3fea5a499d57 that changed
>the behavior and was introduced in v5.8-rc1. I noticed that you are
>targeting this patch for 4.9, 4.14, 4.19, 5.4 and 5.7 stable branches.
>Are you going to backport the commit 3fea5a499d57 as well?

Nope, I'll drop this one. Thanks!

--
Thanks,
Sasha