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[35.238.199.243]) by smtp.gmail.com with ESMTPSA id t8sm1297271ioc.12.2021.04.09.06.39.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Apr 2021 06:39:37 -0700 (PDT) Date: Fri, 9 Apr 2021 13:39:35 +0000 From: Dennis Zhou To: Filipe Manana Cc: Wang Yugui , Vlastimil Babka , linux-mm@kvack.org, linux-btrfs Subject: Re: unexpected -ENOMEM from percpu_counter_init() Message-ID: References: <20210408072800.6C1F.409509F4@e16-tech.com> <20210408171959.2D72.409509F4@e16-tech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: D323DC0007CE X-Stat-Signature: w651grwxtdjthqcyt14wfdpoxwfojen3 Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf06; identity=mailfrom; envelope-from=""; helo=mail-il1-f179.google.com; client-ip=209.85.166.179 X-HE-DKIM-Result: none/none X-HE-Tag: 1617975579-489671 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 09, 2021 at 12:39:38PM +0100, Filipe Manana wrote: > On Thu, Apr 8, 2021 at 4:02 PM Dennis Zhou wrote: > > > > On Thu, Apr 08, 2021 at 03:28:20PM +0100, Filipe Manana wrote: > > > On Thu, Apr 8, 2021 at 2:50 PM Dennis Zhou wrot= e: > > > > > > > > On Thu, Apr 08, 2021 at 05:20:00PM +0800, Wang Yugui wrote: > > > > > Hi, > > > > > > > > > > > On Thu, Apr 08, 2021 at 07:28:01AM +0800, Wang Yugui wrote: > > > > > > > Hi, > > > > > > > > > > > > > > > > > > upper caller: > > > > > > > > > > > nofs_flag =3D memalloc_nofs_save(); > > > > > > > > > > > ret =3D btrfs_drew_lock_init(&root->snapshot_lo= ck); > > > > > > > > > > > memalloc_nofs_restore(nofs_flag); > > > > > > > > > > > > > > > > The issue is here. nofs is set which means percpu attempt= s an atomic > > > > > > > > allocation. If it cannot find anything already allocated = it isn't happy. > > > > > > > > This was done before memalloc_nofs_{save/restore}() were = pervasive. > > > > > > > > > > > > > > > > Percpu should probably try to allocate some pages if poss= ible even if > > > > > > > > nofs is set. > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > I will wait for the patch, and then test it. > > > > > > > > > > > > > > > > > > > I'm currently a bit busy with some other things. Adding suppo= rt I don't > > > > > > think will be much work, just a little bit tricky. > > > > > > > > > > > > I recommend carrying what you have minus the change to reserv= ed percpu > > > > > > memory for now. If I'm the one to write it, I'll cc you. > > > > > > > > > > > > Thanks, > > > > > > Dennis > > > > > > > > > > > > > > > In the recent test, another problem is triggered too with my ex= tended > > > > > percpu buffer size patch. maybe this info is helpful. > > > > > > > > > > problem: > > > > > OS/VGA console is freezed , and no call stace is outputed. > > > > > Just some info is outputed to IPMI/dell iDRAC > > > > > 2 | 04/03/2021 | 11:35:01 | OS Critical Stop #0x46 | Run-tim= e critical stop () | Asserted > > > > > 3 | Linux kernel panic: Fatal excep > > > > > 4 | Linux kernel panic: tion > > > > > 5 | 04/05/2021 | 19:09:14 | OS Critical Stop #0x46 | Run-tim= e critical stop () | Asserted > > > > > 6 | Linux kernel panic: Fatal excep > > > > > 7 | Linux kernel panic: tion > > > > > 8 | 04/06/2021 | 13:08:42 | OS Critical Stop #0x46 | Run-tim= e critical stop () | Asserted > > > > > 9 | Linux kernel panic: Fatal excep > > > > > a | Linux kernel panic: tion > > > > > b | 04/08/2021 | 02:12:46 | OS Critical Stop #0x46 | Run-tim= e critical stop () | Asserted > > > > > c | Linux kernel panic: Fatal excep > > > > > d | Linux kernel panic: tion > > > > > > > > Unfortunately non of the above to me is useful. > > > > > > > > > kernel: at least 5.10.26/5.10.27/5.10.28 > > > > > > > > > > This problem is triggered by our application, NOT xfstests. > > > > > But our applicaiton have some heavy write load just like xfstes= t/generic/476. > > > > > Our application use at most 75% of memory, if still not enough, > > > > > it will write out all buffer info to filesystem. > > > > > > > > Do you use cgroups at all? If yes can you describe the workload p= attern > > > > a bit. > > > > > > > > > This problem is happen in linux kernel 5.10.x, but not happen i= n linux > > > > > kernel 5.4.x. It have high frequency to repduce too. > > > > > > > > Ah. Can you try the following patch? > > > > https://lore.kernel.org/lkml/20210408035736.883861-4-guro@fb.com/ > > > > > > Btw, this has been happening since 5.9. > > > I never managed to find the time to bisect it, but it might be more > > > obvious to you or anyone else with deep experience of mm/percpu of > > > what changed. > > > > > > > Ah I'm sorry about that. It wasn't brought to my attention and I don'= t > > frequent the btrfs slack anymore. I can try and pop in more frequentl= y > > if that would help with these things. >=20 > No worries, I don't think anyone reported it before. >=20 > > > > > It's triggered very frequently with long runs of fsstress on btrfs, > > > such as with test cases btrfs/078 and generic/476 from fstests. > > > It produces a trace like the following: > > > > > > [128063.794597] ------------[ cut here ]------------ > > > [128063.795305] BTRFS: Transaction aborted (error -12) > > > [128063.795831] WARNING: CPU: 0 PID: 1131545 at > > > fs/btrfs/transaction.c:1683 create_pending_snapshot+0xa2a/0xfd0 > > > [btrfs] > > > [128063.796235] Modules linked in: dm_snapshot btrfs dm_thin_pool > > > dm_persistent_data dm_bio_prison dm_bufio dm_log_writes dm_dust > > > dm_flakey dm_mod loop xfs blake2b_generic xor raid6_pq libcrc32c > > > intel_rapl_msr intel_rapl_common kvm_intel kvm irqbypass > > > crct10dif_pclmul g> > > > [128063.798521] CPU: 0 PID: 1131545 Comm: fsstress Tainted: G = W > > > 5.10.0-rc2-btrfs-next-71 #1 > > > [128063.799102] Hardware name: QEMU Standard PC (i440FX + PIIX, 199= 6), > > > BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 > > > [128063.800150] RIP: 0010:create_pending_snapshot+0xa2a/0xfd0 [btrf= s] > > > [128063.800748] Code: 02 72 30 83 f8 fb 0f 84 38 03 00 00 83 f8 e2 = 0f > > > 84 2f 03 00 00 89 c6 48 c7 c7 e8 af c5 c0 48 89 85 78 ff ff ff e8 6= d > > > 29 6b ca <0f> 0b 48 8b 85 78 ff ff ff 89 c1 ba 93 06 00 00 48 c7 c6= 90 > > > a6 c4 > > > [128063.801886] RSP: 0018:ffffaad1444cfd50 EFLAGS: 00010282 > > > [128063.802529] RAX: 0000000000000000 RBX: ffff99c4c0d0b500 RCX: > > > 0000000000000000 > > > [128063.803175] RDX: 0000000000000001 RSI: 0000000000000027 RDI: > > > 00000000ffffffff > > > [128063.803829] RBP: ffffaad1444cfe20 R08: 0000000000000000 R09: > > > 0000000000000000 > > > [128063.804478] R10: 0000000000000000 R11: 0000000000000000 R12: > > > ffff99c70a1a4c10 > > > [128063.805134] R13: ffff99c59e3d0e00 R14: ffff99c70e935d08 R15: > > > 00000000fffffff4 > > > [128063.805816] FS: 00007f0fdd733240(0000) GS:ffff99c7ebe00000(000= 0) > > > knlGS:0000000000000000 > > > [128063.806547] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > > [128063.807264] CR2: 00007f0fdd731000 CR3: 00000001ee3b6003 CR4: > > > 00000000003706f0 > > > [128063.807998] DR0: 0000000000000000 DR1: 0000000000000000 DR2: > > > 0000000000000000 > > > [128063.808707] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: > > > 0000000000000400 > > > [128063.809415] Call Trace: > > > [128063.810172] ? create_pending_snapshots+0xaa/0xd0 [btrfs] > > > [128063.810921] create_pending_snapshots+0xaa/0xd0 [btrfs] > > > [128063.811680] btrfs_commit_transaction+0x2b6/0xb80 [btrfs] > > > [128063.812429] ? finish_wait+0x90/0x90 > > > [128063.813176] ? __ia32_sys_fdatasync+0x20/0x20 > > > [128063.813898] iterate_supers+0x87/0xf0 > > > [128063.814562] ksys_sync+0x60/0xb0 > > > [128063.815214] __do_sys_sync+0xa/0x10 > > > [128063.815879] do_syscall_64+0x33/0x80 > > > [128063.816539] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > > [128063.817191] RIP: 0033:0x7f0fdd829bd7 > > > [128063.817907] Code: ff ff ff ff c3 66 0f 1f 44 00 00 48 8b 15 b1 = 82 > > > 0c 00 f7 d8 64 89 02 b8 ff ff ff ff eb b8 0f 1f 44 00 00 b8 a2 00 0= 0 > > > 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 89 82 0c 00 f7 d8 64= 89 > > > 01 48 > > > [128063.819411] RSP: 002b:00007fff356b8968 EFLAGS: 00000206 ORIG_RA= X: > > > 00000000000000a2 > > > [128063.820233] RAX: ffffffffffffffda RBX: 000055acc4127560 RCX: > > > 00007f0fdd829bd7 > > > [128063.821028] RDX: 00000000ffffffff RSI: 000000002ecb3555 RDI: > > > 00000000000069f4 > > > [128063.821808] RBP: 000000000000c350 R08: 0000000000000014 R09: > > > 00007fff356b893c > > > [128063.822632] R10: 00007fff356b8565 R11: 0000000000000206 R12: > > > 00000000000069f4 > > > [128063.823416] R13: 00007fff356b89d0 R14: 00007fff356b8986 R15: > > > 000055acc4115350 > > > [128063.824249] CPU: 5 PID: 1131545 Comm: fsstress Tainted: G = W > > > 5.10.0-rc2-btrfs-next-71 #1 > > > [128063.824931] Hardware name: QEMU Standard PC (i440FX + PIIX, 199= 6), > > > BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 > > > [128063.826439] Call Trace: > > > [128063.827119] dump_stack+0x8d/0xb5 > > > [128063.827804] ? create_pending_snapshot+0xa2a/0xfd0 [btrfs] > > > [128063.828456] __warn.cold+0x24/0x4b > > > [128063.829100] ? create_pending_snapshot+0xa2a/0xfd0 [btrfs] > > > [128063.829724] report_bug+0xd1/0x100 > > > [128063.830327] handle_bug+0x35/0x80 > > > [128063.830910] exc_invalid_op+0x14/0x70 > > > [128063.831476] asm_exc_invalid_op+0x12/0x20 > > > [128063.832042] RIP: 0010:create_pending_snapshot+0xa2a/0xfd0 [btrf= s] > > > > > > With 5.8 and older, I never got such failures on my test boxes. > > > > > > > Ah. Roman's cgroup percpu changes went in for 5.9. Can you please pat= ch: > > https://lore.kernel.org/lkml/20210408035736.883861-4-guro@fb.com/ > > > > That most likely will have to be cced to stable for 5.9+. >=20 > With that patch applied, +12 hours runs of heavy fsstress and fstests > did not trigger the issue anymore here. Wonderful! Is it okay if I throw your Tested-by: on it? I'm going to send this up tomorrow and have cced stable on the patch as well. >=20 > Thanks Dennis. >=20 > --=20 > Filipe David Manana, >=20 > =E2=80=9CWhether you think you can, or you think you can't =E2=80=94 yo= u're right.=E2=80=9D Thanks, Dennis