So I rebooted with 4.9rc6 with the patch inspired by the thread
"[PATCH] btrfs: limit the number of asynchronous delalloc pages to
reasonable value", but at 512K pages, ie:
diff -u2 fs/btrfs/inode.c ../linux-4.9-rc6/fs/btrfs/
--- fs/btrfs/inode.c 2016-11-13 13:32:32.000000000 -0500
+++ ../linux-4.9-rc6/fs/btrfs/inode.c 2016-11-23 08:31:02.145669550 -0500
@@ -1159,5 +1159,5 @@
unsigned long nr_pages;
u64 cur_end;
- int limit = 10 * SZ_1M;
+ int limit = SZ_512K;
clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, EXTENT_LOCKED,
System still OOM'd after a few hours of rsync copying & deleting
files, but it didn't panic this time which was nice ;-) I then set:
echo 500 >> /proc/sys/vm/watermark_scale_factor
echo 3 >> /proc/sys/vm/dirty_background_ratio
and system has been running rsync fine for most of a day. system
memory load is noticably different in sar -r after changing the vm
params, rsync during OOM:
12:00:01 AM kbmemfree kbmemused %memused kbbuffers kbcached
kbcommit %commit kbactive kbinact kbdirty
03:25:05 AM 158616 32836640 99.52 72376 30853268
2942644 3.62 26048876 4977872 4936488
03:30:36 AM 157700 32837556 99.52 72468 30944468
2940028 3.62 26070084 4957328 4957432
03:35:02 AM 1802144 31193112 94.54 72560 29266432
2944352 3.62 26184324 3182048 187784
03:40:32 AM 157272 32837984 99.52 72648 30934432
3007244 3.70 26102636 4930744 4927832
03:45:05 AM 158288 32836968 99.52 72896 30980504
412108 0.51 26089920 4959668 4977556
running rsync after tuning VM params:
08:35:01 AM 1903352 31091904 94.23 232772 26603624
2680952 3.30 24133864 5019748 1229964
08:40:01 AM 2878552 30116704 91.28 232800 25641520
2697356 3.32 24158248 4039372 2864656
08:45:01 AM 3482616 29512640 89.45 232656 25043068
2696144 3.32 24087376 3526164 1897192
08:50:01 AM 3590672 29404584 89.12 232856 24962856
2704196 3.33 24078188 3451400 666760
08:55:01 AM 2064900 30930356 93.74 234800 26480996
2730384 3.36 24009244 5044012 50028
On Tue, Nov 22, 2016 at 9:48 AM, Vlastimil Babka <vbabka@xxxxxxx> wrote:
> On 11/22/2016 02:58 PM, E V wrote:
>> System OOM'd several times last night with 4.8.10, I attached the
>> page_owner output from a morning cat ~8 hours after OOM's to the
>> bugzilla case, split and compressed to fit under the 5M attachment
>> limit. Let me know if you need anything else.
>
> Looks like for some reason, the stack saving produces garbage stacks
> that only repeat save_stack_trace and save_stack functions :/
>
> But judging from gfp flags and page flags, most pages seem to be
> allocated with:
>
> mask 0x2400840(GFP_NOFS|__GFP_NOFAIL)
>
> and page flags:
>
> 0x20000000000006c(referenced|uptodate|lru|active)
> or
> 0x20000000000016c(referenced|uptodate|lru|active|owner_priv_1)
> or
> 0x20000000000086c(referenced|uptodate|lru|active|private)
>
> While GFP_HIGHUSER_MOVABLE (which I would expect on lru) are less frequent.
>
> Example:
>> grep GFP_NOFS page_owner_after_af | wc -l
> 973596
>> grep GFP_HIGHUSER_MOVABLE page_owner_after_af | wc -l
> 158879
>> grep GFP_NOFAIL page_owner_after_af | wc -l
> 971442
>
> grepping for btrfs shows that at least some stacks for NOFS/NOFAIL pages
> imply it:
> clear_state_bit+0x135/0x1c0 [btrfs]
> or
> add_delayed_tree_ref+0xbf/0x170 [btrfs]
> or
> __btrfs_map_block+0x6a8/0x1200 [btrfs]
> or
> btrfs_buffer_uptodate+0x48/0x70 [btrfs]
> or
> btrfs_set_path_blocking+0x34/0x60 [btrfs]
>
> and some more variants.
>
> So looks like the pages contain btrfs metadata, are on file lru and from
> previous checks of /proc/kpagecount we know that they most likely have
> page_count() == 0 but are not freed. Could btrfs guys provide some
> insight here?
>
>> On Fri, Nov 18, 2016 at 10:02 AM, E V <eliventer@xxxxxxxxx> wrote:
>>> Yes, the short window between the stalls and the panic makes it
>>> difficult to manually check much. I could setup a cron every 5 minutes
>>> or so if you want. Also, I see the OOM's in 4.8, but it has yet to
>>> panic on me. Where as 4.9rc has panic'd both times I've booted it, so
>>> depending on what you want to look at it might be easier to
>>> investigate on 4.8. Let me know, I can turn on a couple of the DEBUG
>>> config's and build a new 4.8.8. Never looked into a netconsole or
>>> serial console. I think just getting the system to use a higher res
>>> console would be an improvement, but the OOM's seemed to be the root
>>> cause of the panic so I haven't spent any time looking into that as of
>>> yet,
>>>
>>> Thanks,
>>> -Eli
>>>
>>> On Fri, Nov 18, 2016 at 6:54 AM, Tetsuo Handa
>>> <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote:
>>>> On 2016/11/18 6:49, Vlastimil Babka wrote:
>>>>> On 11/16/2016 02:39 PM, E V wrote:
>>>>>> System panic'd overnight running 4.9rc5 & rsync. Attached a photo of
>>>>>> the stack trace, and the 38 call traces in a 2 minute window shortly
>>>>>> before, to the bugzilla case for those not on it's e-mail list:
>>>>>>
>>>>>> https://bugzilla.kernel.org/show_bug.cgi?id=186671
>>>>>
>>>>> The panic screenshot has only the last part, but the end marker says
>>>>> it's OOM with no killable processes. The DEBUG_VM config thus didn't
>>>>> trigger anything, and still there's tons of pagecache, mostly clean,
>>>>> that's not being reclaimed.
>>>>>
>>>>> Could you now try this?
>>>>> - enable CONFIG_PAGE_OWNER
>>>>> - boot with kernel option: page_owner=on
>>>>> - after the first oom, "cat /sys/kernel/debug/page_owner > file"
>>>>> - provide the file (compressed, it will be quite large)
>>>>
>>>> Excuse me for a noise, but do we really need to do
>>>> "cat /sys/kernel/debug/page_owner > file" after the first OOM killer
>>>> invocation? I worry that it might be too difficult to do.
>>>> Shouldn't we rather do "cat /sys/kernel/debug/page_owner > file"
>>>> hourly and compare tendency between the latest one and previous one?
>>>>
>>>> This system has swap, and /var/log/messages before panic
>>>> reports that swapin was stalling at memory allocation.
>>>>
>>>> ----------------------------------------
>>>> [130346.262510] dsm_sa_datamgrd: page allocation stalls for 52400ms, order:0, mode:0x24200ca(GFP_HIGHUSER_MOVABLE)
>>>> [130346.262572] CPU: 1 PID: 3622 Comm: dsm_sa_datamgrd Tainted: G W I 4.9.0-rc5 #2
>>>> [130346.262662] 0000000000000000 ffffffff8129ba69 ffffffff8170e4c8 ffffc90003ccb8d8
>>>> [130346.262714] ffffffff8113449f 024200ca1ca11b40 ffffffff8170e4c8 ffffc90003ccb880
>>>> [130346.262765] ffffffff00000010 ffffc90003ccb8e8 ffffc90003ccb898 ffff88041f226e80
>>>> [130346.262817] Call Trace:
>>>> [130346.262843] [<ffffffff8129ba69>] ? dump_stack+0x46/0x5d
>>>> [130346.262872] [<ffffffff8113449f>] ? warn_alloc+0x11f/0x140
>>>> [130346.262899] [<ffffffff81134d7b>] ? __alloc_pages_slowpath+0x84b/0xa80
>>>> [130346.262929] [<ffffffff81135260>] ? __alloc_pages_nodemask+0x2b0/0x2f0
>>>> [130346.262960] [<ffffffff8117f1be>] ? alloc_pages_vma+0xbe/0x260
>>>> [130346.262989] [<ffffffff8112af02>] ? pagecache_get_page+0x22/0x280
>>>> [130346.263019] [<ffffffff81171b68>] ? __read_swap_cache_async+0x118/0x1a0
>>>> [130346.263048] [<ffffffff81171bff>] ? read_swap_cache_async+0xf/0x30
>>>> [130346.263077] [<ffffffff81171d8e>] ? swapin_readahead+0x16e/0x1c0
>>>> [130346.263106] [<ffffffff812a0f6e>] ? radix_tree_lookup_slot+0xe/0x20
>>>> [130346.263135] [<ffffffff8112ac84>] ? find_get_entry+0x14/0x130
>>>> [130346.263162] [<ffffffff8112af02>] ? pagecache_get_page+0x22/0x280
>>>> [130346.263193] [<ffffffff8115cb1f>] ? do_swap_page+0x44f/0x5f0
>>>> [130346.263220] [<ffffffff812a0f02>] ? __radix_tree_lookup+0x62/0xc0
>>>> [130346.263249] [<ffffffff8115e91a>] ? handle_mm_fault+0x66a/0xf00
>>>> [130346.263277] [<ffffffff8112ac84>] ? find_get_entry+0x14/0x130
>>>> [130346.263305] [<ffffffff8104a245>] ? __do_page_fault+0x1c5/0x490
>>>> [130346.263336] [<ffffffff8150e322>] ? page_fault+0x22/0x30
>>>> [130346.263364] [<ffffffff812a7cac>] ? copy_user_generic_string+0x2c/0x40
>>>> [130346.263395] [<ffffffff811adc1d>] ? set_fd_set+0x1d/0x30
>>>> [130346.263422] [<ffffffff811ae905>] ? core_sys_select+0x1a5/0x260
>>>> [130346.263450] [<ffffffff811a913a>] ? getname_flags+0x6a/0x1e0
>>>> [130346.263479] [<ffffffff8119ef25>] ? cp_new_stat+0x115/0x130
>>>> [130346.263509] [<ffffffff810bf01f>] ? ktime_get_ts64+0x3f/0xf0
>>>> [130346.263537] [<ffffffff811aea65>] ? SyS_select+0xa5/0xe0
>>>> [130346.263564] [<ffffffff8150c6a0>] ? entry_SYSCALL_64_fastpath+0x13/0x94
>>>> ----------------------------------------
>>>>
>>>> Under such situation, trying to login and execute /bin/cat could take minutes.
>>>> Also, writing to btrfs and ext4 seems to be stalling. The btrfs one is a
>>>> situation where WQ_MEM_RECLAIM kernel workqueue is unable to make progress.
>>>>
>>>> ----------------------------------------
>>>> [130420.008231] kworker/u34:21: page allocation stalls for 35028ms, order:0, mode:0x2400840(GFP_NOFS|__GFP_NOFAIL)
>>>> [130420.008287] CPU: 5 PID: 24286 Comm: kworker/u34:21 Tainted: G W I 4.9.0-rc5 #2
>>>> [130420.008401] Workqueue: btrfs-extent-refs btrfs_extent_refs_helper [btrfs]
>>>> [130420.008432] 0000000000000000 ffffffff8129ba69 ffffffff8170e4c8 ffffc900087836a0
>>>> [130420.008483] ffffffff8113449f 024008401e3f1b40 ffffffff8170e4c8 ffffc90008783648
>>>> [130420.008534] ffffffff00000010 ffffc900087836b0 ffffc90008783660 ffff88041ecc4340
>>>> [130420.008586] Call Trace:
>>>> [130420.008611] [<ffffffff8129ba69>] ? dump_stack+0x46/0x5d
>>>> [130420.008640] [<ffffffff8113449f>] ? warn_alloc+0x11f/0x140
>>>> [130420.008667] [<ffffffff81134d7b>] ? __alloc_pages_slowpath+0x84b/0xa80
>>>> [130420.008707] [<ffffffffa020c432>] ? search_bitmap+0xc2/0x140 [btrfs]
>>>> [130420.008736] [<ffffffff81135260>] ? __alloc_pages_nodemask+0x2b0/0x2f0
>>>> [130420.008766] [<ffffffff8117dbda>] ? alloc_pages_current+0x8a/0x110
>>>> [130420.008796] [<ffffffff8112afcc>] ? pagecache_get_page+0xec/0x280
>>>> [130420.008836] [<ffffffffa01e9aa8>] ? alloc_extent_buffer+0x108/0x430 [btrfs]
>>>> [130420.008875] [<ffffffffa01b4108>] ? btrfs_alloc_tree_block+0x118/0x4d0 [btrfs]
>>>> [130420.008927] [<ffffffffa019ae38>] ? __btrfs_cow_block+0x148/0x5d0 [btrfs]
>>>> [130420.008964] [<ffffffffa019b464>] ? btrfs_cow_block+0x114/0x1d0 [btrfs]
>>>> [130420.009001] [<ffffffffa019f1d6>] ? btrfs_search_slot+0x206/0xa40 [btrfs]
>>>> [130420.009039] [<ffffffffa01a6089>] ? lookup_inline_extent_backref+0xd9/0x620 [btrfs]
>>>> [130420.009095] [<ffffffffa01e4e74>] ? set_extent_bit+0x24/0x30 [btrfs]
>>>> [130420.009124] [<ffffffff8118567f>] ? kmem_cache_alloc+0x17f/0x1b0
>>>> [130420.009161] [<ffffffffa01a7b1f>] ? __btrfs_free_extent.isra.69+0xef/0xd10 [btrfs]
>>>> [130420.009215] [<ffffffffa0214346>] ? btrfs_merge_delayed_refs+0x56/0x6f0 [btrfs]
>>>> [130420.009269] [<ffffffffa01ac545>] ? __btrfs_run_delayed_refs+0x745/0x1320 [btrfs]
>>>> [130420.009314] [<ffffffff810801ef>] ? ttwu_do_wakeup+0xf/0xe0
>>>> [130420.009351] [<ffffffffa01b0000>] ? btrfs_run_delayed_refs+0x90/0x2b0 [btrfs]
>>>> [130420.009404] [<ffffffffa01b02a4>] ? delayed_ref_async_start+0x84/0xa0 [btrfs]
>>>> [130420.009459] [<ffffffffa01f82a3>] ? normal_work_helper+0xc3/0x2f0 [btrfs]
>>>> [130420.009490] [<ffffffff81071efb>] ? process_one_work+0x14b/0x400
>>>> [130420.009518] [<ffffffff8107251d>] ? worker_thread+0x5d/0x470
>>>> [130420.009546] [<ffffffff810724c0>] ? rescuer_thread+0x310/0x310
>>>> [130420.009573] [<ffffffff8105ed54>] ? do_group_exit+0x34/0xb0
>>>> [130420.009601] [<ffffffff810772bb>] ? kthread+0xcb/0xf0
>>>> [130420.009627] [<ffffffff810771f0>] ? kthread_park+0x50/0x50
>>>> [130420.009655] [<ffffffff8150c8d2>] ? ret_from_fork+0x22/0x30
>>>> ----------------------------------------
>>>>
>>>> ----------------------------------------
>>>> [130438.436025] jbd2/dm-0-8: page allocation stalls for 10492ms, order:0, mode:0x2420848(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE)
>>>> [130438.436095] CPU: 2 PID: 1838 Comm: jbd2/dm-0-8 Tainted: G W I 4.9.0-rc5 #2
>>>> [130438.436184] 0000000000000000 ffffffff8129ba69 ffffffff8170e4c8 ffffc90003e13728
>>>> [130438.436237] ffffffff8113449f 0242084800000200 ffffffff8170e4c8 ffffc90003e136d0
>>>> [130438.436289] 0000000100000010 ffffc90003e13738 ffffc90003e136e8 0000000000000001
>>>> [130438.436340] Call Trace:
>>>> [130438.436368] [<ffffffff8129ba69>] ? dump_stack+0x46/0x5d
>>>> [130438.436399] [<ffffffff8113449f>] ? warn_alloc+0x11f/0x140
>>>> [130438.436426] [<ffffffff81134d7b>] ? __alloc_pages_slowpath+0x84b/0xa80
>>>> [130438.436455] [<ffffffff81135260>] ? __alloc_pages_nodemask+0x2b0/0x2f0
>>>> [130438.436488] [<ffffffff8117dbda>] ? alloc_pages_current+0x8a/0x110
>>>> [130438.436518] [<ffffffff8112afcc>] ? pagecache_get_page+0xec/0x280
>>>> [130438.436549] [<ffffffff811cc051>] ? __getblk_gfp+0xf1/0x320
>>>> [130438.436593] [<ffffffffa02bc774>] ? ext4_get_branch+0xa4/0x130 [ext4]
>>>> [130438.436628] [<ffffffffa02bd24b>] ? ext4_ind_map_blocks+0xcb/0xb10 [ext4]
>>>> [130438.436658] [<ffffffff8108807e>] ? update_curr+0x7e/0x100
>>>> [130438.436688] [<ffffffff810bfe61>] ? ktime_get+0x31/0xa0
>>>> [130438.436716] [<ffffffff8112e329>] ? mempool_alloc+0x59/0x170
>>>> [130438.436743] [<ffffffff8108807e>] ? update_curr+0x7e/0x100
>>>> [130438.436775] [<ffffffffa0280813>] ? ext4_map_blocks+0x3c3/0x630 [ext4]
>>>> [130438.436808] [<ffffffffa0280ae4>] ? _ext4_get_block+0x64/0xc0 [ext4]
>>>> [130438.436838] [<ffffffff811ca6a7>] ? generic_block_bmap+0x37/0x50
>>>> [130438.436870] [<ffffffffa027fc57>] ? ext4_bmap+0x37/0xd0 [ext4]
>>>> [130438.436901] [<ffffffffa008a5e1>] ? jbd2_journal_bmap+0x21/0x70 [jbd2]
>>>> [130438.436932] [<ffffffffa008a6be>] ? jbd2_journal_get_descriptor_buffer+0x1e/0xc0 [jbd2]
>>>> [130438.436979] [<ffffffffa0086aa8>] ? jbd2_journal_write_revoke_records+0x198/0x2b0 [jbd2]
>>>> [130438.437026] [<ffffffffa0083236>] ? jbd2_journal_commit_transaction+0x5d6/0x19f0 [jbd2]
>>>> [130438.437071] [<ffffffff8108807e>] ? update_curr+0x7e/0x100
>>>> [130438.437099] [<ffffffff8108c8fc>] ? dequeue_task_fair+0x5dc/0x1120
>>>> [130438.437127] [<ffffffff8108f61c>] ? pick_next_task_fair+0x12c/0x420
>>>> [130438.437157] [<ffffffffa00884e8>] ? kjournald2+0xc8/0x250 [jbd2]
>>>> [130438.437187] [<ffffffff810948e0>] ? wake_up_atomic_t+0x30/0x30
>>>> [130438.437216] [<ffffffffa0088420>] ? commit_timeout+0x10/0x10 [jbd2]
>>>> [130438.437247] [<ffffffff810772bb>] ? kthread+0xcb/0xf0
>>>> [130438.437273] [<ffffffff810771f0>] ? kthread_park+0x50/0x50
>>>> [130438.437304] [<ffffffff8150c8d2>] ? ret_from_fork+0x22/0x30
>>>> ----------------------------------------
>>>>
>>>> Under such situation, saving /sys/kernel/debug/page_owner to a file might
>>>> be impossible. And, once the stalling started, it took less than 5 minutes
>>>> before the kernel panics due to "Out of memory and no killable process".
>>>> This could happen when E V is offline.
>>>>
>>>> Since rsyslogd is likely be killed by the OOM killer for situations like
>>>> this, E V might want to try serial console or netconsole for saving kernel
>>>> messages reliably.
>>>>
>>>> I don't know what we will find by analyzing /sys/kernel/debug/page_owner ,
>>>> but if something is wrong, can't we try whether
>>>> "echo 3 > /proc/sys/vm/drop_caches" before the stalling starts helps.
>>>>
>>>> I guess that this problem became visible by OOM detection rework which
>>>> went to Linux 4.7. I don't know what "free_pcp:0kB local_pcp:0kB" means
>>>> (get_page_from_freelist() for any order is failng?), but in general I think
>>>> this /var/log/messages showed that free_pcp: and local_pcp: remains small.
>>>>
>
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