From: David Howells <dhowells@redhat.com>
To: linux-cachefs@redhat.com
Cc: linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org,
hjayasur@redhat.com, jlayton@redhat.com,
linux-kernel@vger.kernel.org
Subject: [PATCH 3/8] FS-Cache: Don't sleep in page release if __GFP_FS is not set
Date: Fri, 03 May 2013 01:33:30 +0100 [thread overview]
Message-ID: <20130503003330.14952.53672.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <20130503003316.14952.51791.stgit@warthog.procyon.org.uk>
Don't sleep in __fscache_maybe_release_page() if __GFP_FS is not set. This
goes some way towards mitigating fscache deadlocking against ext4 by way of
the allocator, eg:
INFO: task flush-8:0:24427 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
flush-8:0 D ffff88003e2b9fd8 0 24427 2 0x00000000
ffff88003e2b9138 0000000000000046 ffff880012e3a040 ffff88003e2b9fd8
0000000000011c80 ffff88003e2b9fd8 ffffffff81a10400 ffff880012e3a040
0000000000000002 ffff880012e3a040 ffff88003e2b9098 ffffffff8106dcf5
Call Trace:
[<ffffffff8106dcf5>] ? __lock_is_held+0x31/0x53
[<ffffffff81219b61>] ? radix_tree_lookup_element+0xf4/0x12a
[<ffffffff81454bed>] schedule+0x60/0x62
[<ffffffffa01d349c>] __fscache_wait_on_page_write+0x8b/0xa5 [fscache]
[<ffffffff810498a8>] ? __init_waitqueue_head+0x4d/0x4d
[<ffffffffa01d393a>] __fscache_maybe_release_page+0x30c/0x324 [fscache]
[<ffffffffa01d369a>] ? __fscache_maybe_release_page+0x6c/0x324 [fscache]
[<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170
[<ffffffffa01fd7b2>] nfs_fscache_release_page+0x68/0x94 [nfs]
[<ffffffffa01ef73e>] nfs_release_page+0x7e/0x86 [nfs]
[<ffffffff810aa553>] try_to_release_page+0x32/0x3b
[<ffffffff810b6c70>] shrink_page_list+0x535/0x71a
[<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170
[<ffffffff810b7352>] shrink_inactive_list+0x20a/0x2dd
[<ffffffff81071a13>] ? mark_held_locks+0xbe/0xea
[<ffffffff810b7a65>] shrink_lruvec+0x34c/0x3eb
[<ffffffff810b7bd3>] do_try_to_free_pages+0xcf/0x355
[<ffffffff810b7fc8>] try_to_free_pages+0x9a/0xa1
[<ffffffff810b08d2>] __alloc_pages_nodemask+0x494/0x6f7
[<ffffffff810d9a07>] kmem_getpages+0x58/0x155
[<ffffffff810dc002>] fallback_alloc+0x120/0x1f3
[<ffffffff8106db23>] ? trace_hardirqs_off+0xd/0xf
[<ffffffff810dbed3>] ____cache_alloc_node+0x177/0x186
[<ffffffff81162a6c>] ? ext4_init_io_end+0x1c/0x37
[<ffffffff810dc403>] kmem_cache_alloc+0xf1/0x176
[<ffffffff810b17ac>] ? test_set_page_writeback+0x101/0x113
[<ffffffff81162a6c>] ext4_init_io_end+0x1c/0x37
[<ffffffff81162ce4>] ext4_bio_write_page+0x20f/0x3af
[<ffffffff8115cc02>] mpage_da_submit_io+0x26e/0x2f6
[<ffffffff811088e5>] ? __find_get_block_slow+0x38/0x133
[<ffffffff81161348>] mpage_da_map_and_submit+0x3a7/0x3bd
[<ffffffff81161a60>] ext4_da_writepages+0x30d/0x426
[<ffffffff810b3359>] do_writepages+0x1c/0x2a
[<ffffffff81102f4d>] __writeback_single_inode+0x3e/0xe5
[<ffffffff81103995>] writeback_sb_inodes+0x1bd/0x2f4
[<ffffffff81103b3b>] __writeback_inodes_wb+0x6f/0xb4
[<ffffffff81103c81>] wb_writeback+0x101/0x195
[<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170
[<ffffffff811043aa>] ? wb_do_writeback+0xaa/0x173
[<ffffffff8110434a>] wb_do_writeback+0x4a/0x173
[<ffffffff81071bbc>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81038554>] ? del_timer+0x4b/0x5b
[<ffffffff811044e0>] bdi_writeback_thread+0x6d/0x147
[<ffffffff81104473>] ? wb_do_writeback+0x173/0x173
[<ffffffff81048fbc>] kthread+0xd0/0xd8
[<ffffffff81455eb2>] ? _raw_spin_unlock_irq+0x29/0x3e
[<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55
[<ffffffff81456aac>] ret_from_fork+0x7c/0xb0
[<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55
2 locks held by flush-8:0/24427:
#0: (&type->s_umount_key#41){.+.+..}, at: [<ffffffff810e3b73>] grab_super_passive+0x4c/0x76
#1: (jbd2_handle){+.+...}, at: [<ffffffff81190d81>] start_this_handle+0x475/0x4ea
The problem here is that another thread, which is attempting to write the
to-be-stored NFS page to the on-ext4 cache file is waiting for the journal
lock, eg:
INFO: task kworker/u:2:24437 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u:2 D ffff880039589768 0 24437 2 0x00000000
ffff8800395896d8 0000000000000046 ffff8800283bf040 ffff880039589fd8
0000000000011c80 ffff880039589fd8 ffff880039f0b040 ffff8800283bf040
0000000000000006 ffff8800283bf6b8 ffff880039589658 ffffffff81071a13
Call Trace:
[<ffffffff81071a13>] ? mark_held_locks+0xbe/0xea
[<ffffffff81455e73>] ? _raw_spin_unlock_irqrestore+0x3a/0x50
[<ffffffff81071b53>] ? trace_hardirqs_on_caller+0x114/0x170
[<ffffffff81071bbc>] ? trace_hardirqs_on+0xd/0xf
[<ffffffff81454bed>] schedule+0x60/0x62
[<ffffffff81190c23>] start_this_handle+0x317/0x4ea
[<ffffffff810498a8>] ? __init_waitqueue_head+0x4d/0x4d
[<ffffffff81190fcc>] jbd2__journal_start+0xb3/0x12e
[<ffffffff81176606>] __ext4_journal_start_sb+0xb2/0xc6
[<ffffffff8115f137>] ext4_da_write_begin+0x109/0x233
[<ffffffff810a964d>] generic_file_buffered_write+0x11a/0x264
[<ffffffff811032cf>] ? __mark_inode_dirty+0x2d/0x1ee
[<ffffffff810ab1ab>] __generic_file_aio_write+0x2a5/0x2d5
[<ffffffff810ab24a>] generic_file_aio_write+0x6f/0xd0
[<ffffffff81159a2c>] ext4_file_write+0x38c/0x3c4
[<ffffffff810e0915>] do_sync_write+0x91/0xd1
[<ffffffffa00a17f0>] cachefiles_write_page+0x26f/0x310 [cachefiles]
[<ffffffffa01d470b>] fscache_write_op+0x21e/0x37a [fscache]
[<ffffffff81455eb2>] ? _raw_spin_unlock_irq+0x29/0x3e
[<ffffffffa01d2479>] fscache_op_work_func+0x78/0xd7 [fscache]
[<ffffffff8104455a>] process_one_work+0x232/0x3a8
[<ffffffff810444ff>] ? process_one_work+0x1d7/0x3a8
[<ffffffff81044ee0>] worker_thread+0x214/0x303
[<ffffffff81044ccc>] ? manage_workers+0x245/0x245
[<ffffffff81048fbc>] kthread+0xd0/0xd8
[<ffffffff81455eb2>] ? _raw_spin_unlock_irq+0x29/0x3e
[<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55
[<ffffffff81456aac>] ret_from_fork+0x7c/0xb0
[<ffffffff81048eec>] ? __init_kthread_worker+0x55/0x55
4 locks held by kworker/u:2/24437:
#0: (fscache_operation){.+.+.+}, at: [<ffffffff810444ff>] process_one_work+0x1d7/0x3a8
#1: ((&op->work)){+.+.+.}, at: [<ffffffff810444ff>] process_one_work+0x1d7/0x3a8
#2: (sb_writers#14){.+.+.+}, at: [<ffffffff810ab22c>] generic_file_aio_write+0x51/0xd0
#3: (&sb->s_type->i_mutex_key#19){+.+.+.}, at: [<ffffffff810ab236>] generic_file_aio_write+0x5b/0x
fscache already tries to cancel pending stores, but it can't cancel a write
for which I/O is already in progress.
An alternative would be to accept writing garbage to the cache under extreme
circumstances and to kill the afflicted cache object if we have to do this.
However, we really need to know how strapped the allocator is before deciding
to do that.
Signed-off-by: David Howells <dhowells@redhat.com>
---
fs/fscache/page.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/fscache/page.c b/fs/fscache/page.c
index 4882c80..42f8f2d 100644
--- a/fs/fscache/page.c
+++ b/fs/fscache/page.c
@@ -109,7 +109,7 @@ page_busy:
* allocator as the work threads writing to the cache may all end up
* sleeping on memory allocation, so we may need to impose a timeout
* too. */
- if (!(gfp & __GFP_WAIT)) {
+ if (!(gfp & __GFP_WAIT) || !(gfp & __GFP_FS)) {
fscache_stat(&fscache_n_store_vmscan_busy);
return false;
}
next prev parent reply other threads:[~2013-05-03 0:33 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-03 0:33 [PATCH 0/8] Fix assorted FS-Cache issues David Howells
2013-05-03 0:33 ` [PATCH 1/8] fs/fscache: remove spin_lock() from the condition in while() David Howells
2013-05-03 0:33 ` [PATCH 2/8] CacheFiles: name i_mutex lock class explicitly David Howells
2013-05-03 0:33 ` David Howells [this message]
2013-05-03 0:33 ` [PATCH 4/8] FS-Cache: Uninline fscache_object_init() David Howells
2013-05-03 0:33 ` [PATCH 5/8] FS-Cache: Wrap checks on object state David Howells
2013-05-03 0:33 ` [PATCH 6/8] Add wait_on_atomic_t() and wake_up_atomic_t() David Howells
2013-05-03 0:33 ` [PATCH 7/8] FS-Cache: Fix object state machine to have separate work and wait states David Howells
2013-05-03 0:33 ` [PATCH 8/8] FS-Cache: Simplify cookie retention for fscache_objects, fixing access problems David Howells
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20130503003330.14952.53672.stgit@warthog.procyon.org.uk \
--to=dhowells@redhat.com \
--cc=hjayasur@redhat.com \
--cc=jlayton@redhat.com \
--cc=linux-cachefs@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).