[Devel] [PATCH rh7] ploop: use GFP_NOIO in ploop_make_request

Mon Aug 31 23:28:31 PDT 2015

On 31.08.2015 16:59, Konstantin Khorenko wrote:
> Maxim, please review.
> 
> Do we need the same in PCS6?

yes, backport to rh6 is required because of
https://bugs.openvz.org/browse/OVZ-6293

1294400.800014] INFO: task jbd2/ploop27926:1692 blocked for more than 120 seconds.
[1294400.800121] Not tainted 2.6.32-042stab108.1 #1
[1294400.800177] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[1294400.800285] jbd2/ploop279 D ffff88081950e400 0 1692 2 0 0x00000080
[1294400.800393] ffff88080dde4fe0 0000000000000046 0000000000000000 ffff88060dac1000
[1294400.800502] 0005120000000000 ffff88081b2c4ae0 0004991706322912 0000000000000002
[1294400.800615] ffff88080dde4fb8 0000000000000000 000000014d2b4e18 0000000000000000
[1294400.800724] Call Trace:
[1294400.800777] [<ffffffff81536075>] schedule_timeout+0x215/0x2e0
[1294400.800836] [<ffffffff81015059>] ? read_tsc+0x9/0x20
[1294400.800893] [<ffffffff810b4801>] ? ktime_get_ts+0xb1/0xf0
[1294400.800951] [<ffffffff81015059>] ? read_tsc+0x9/0x20
[1294400.801008] [<ffffffff810b4801>] ? ktime_get_ts+0xb1/0xf0
[1294400.801066] [<ffffffff8153460f>] io_schedule_timeout+0x7f/0xd0
[1294400.801125] [<ffffffff815359e4>] wait_for_completion_io+0xe4/0x120
[1294400.801185] [<ffffffff81065c00>] ? default_wake_function+0x0/0x20
[1294400.801246] [<ffffffff81286126>] blkdev_issue_discard+0x216/0x230
[1294400.801305] [<ffffffff81189875>] scan_swap_map+0x385/0x640
[1294400.801362] [<ffffffff81189c6d>] get_swap_page+0x9d/0x140
[1294400.801420] [<ffffffff81186e87>] add_to_swap+0x17/0x90
[1294400.801478] [<ffffffff8115a6ce>] shrink_page_list.clone.0+0x2de/0x900
[1294400.801537] [<ffffffff8115bece>] shrink_inactive_list+0x3be/0xb10
[1294400.801600] [<ffffffff81015059>] ? read_tsc+0x9/0x20
[1294400.801660] [<ffffffff8115ca50>] shrink_lruvec+0x430/0x600
[1294400.801718] [<ffffffff8115cea7>] shrink_zone+0x287/0x3d0
[1294400.801775] [<ffffffff8115ec28>] do_try_to_free_pages+0x588/0xa60
[1294400.801834] [<ffffffff8115f31b>] try_to_free_pages+0x8b/0x120
[1294400.801894] [<ffffffff8114fde1>] __alloc_pages_nodemask+0x671/0xb50
[1294400.801954] [<ffffffff8119ac79>] kmem_getpages+0x59/0x140
[1294400.802011] [<ffffffff8119cdcb>] fallback_alloc+0x1bb/0x260
[1294400.802069] [<ffffffff8119cb59>] ____cache_alloc_node+0x99/0x150
[1294400.802128] [<ffffffff8119db63>] kmem_cache_alloc+0x173/0x1e0
[1294400.802186] [<ffffffff81140de5>] mempool_alloc_slab+0x15/0x20
[1294400.802244] [<ffffffff81140f87>] mempool_alloc+0x67/0x170
[1294400.802302] [<ffffffff8119ac79>] ? kmem_getpages+0x59/0x140
[1294400.802361] [<ffffffff811f494e>] bio_alloc_bioset+0x3e/0xf0
[1294400.802419] [<ffffffff811f4aa5>] bio_alloc+0x15/0x30
[1294400.802478] [<ffffffffa04880e8>] ploop_make_request+0x5a8/0xa30 [ploop]
[1294400.802538] [<ffffffff8127d780>] generic_make_request+0x240/0x550
[1294400.802599] [<ffffffff8127db13>] submit_bio+0x83/0x1c0
[1294400.802659] [<ffffffff811f496b>] ? bio_alloc_bioset+0x5b/0xf0
[1294400.802719] [<ffffffff811ee41d>] submit_bh+0x11d/0x1e0
[1294400.802778] [<ffffffffa00a8c18>] jbd2_journal_commit_transaction+0x5a8/0x1500 [jbd2]
[1294400.802888] [<ffffffff810097dd>] ? __switch_to+0x13d/0x320
[1294400.802946] [<ffffffff8108f90b>] ? try_to_del_timer_sync+0x7b/0xe0
[1294400.803008] [<ffffffffa00aebb8>] kjournald2+0xb8/0x220 [jbd2]
[1294400.803066] [<ffffffff810a8860>] ? autoremove_wake_function+0x0/0x40
[1294400.803127] [<ffffffffa00aeb00>] ? kjournald2+0x0/0x220 [jbd2]
[1294400.803185] [<ffffffff810a846e>] kthread+0x9e/0xc0
[1294400.803242] [<ffffffff8100c38a>] child_rip+0xa/0x20
[1294400.803298] [<ffffffff810a83d0>] ? kthread+0x0/0xc0
[1294400.803355] [<ffffffff8100c380>] ? child_rip+0x0/0x20


> -- 
> Best regards,
> 
> Konstantin Khorenko,
> Virtuozzo Linux Kernel Team
> 
> On 08/17/2015 04:30 PM, Vladimir Davydov wrote:
>> Currently, we use GFP_NOFS, which may result in a dead lock as follows:
>>
>> filemap_fault
>>   do_mpage_readpage
>>    submit_bio
>>     generic_make_request                 initializes current->bio_list
>>                                          calls make_request_fn
>>      ploop_make_request
>>       bio_alloc(GFP_NOFS)
>>        kmem_cache_alloc
>>         memcg_charge_kmem
>>          try_to_free_mem_cgroup_pages
>>           swap_writepage
>>            generic_make_request          puts bio on current->bio_list
>>          try_to-free_mem_cgroup_pages
>>           wait_on_page_writeback
>>
>> The wait_on_page_writeback will never complete then, because the
>> corresponding bio is on current->bio_list and for it to get to the queue
>> we must return from ploop_make_request first.
>>
>> The stack trace of a hung task:
>>
>> [<ffffffff8115ae2e>] sleep_on_page+0xe/0x20
>> [<ffffffff8115abb6>] wait_on_page_bit+0x86/0xb0
>> [<ffffffff8116f4b2>] shrink_page_list+0x6e2/0xaf0
>> [<ffffffff8116ff2b>] shrink_inactive_list+0x1cb/0x610
>> [<ffffffff81170ab5>] shrink_lruvec+0x395/0x790
>> [<ffffffff81171031>] shrink_zone+0x181/0x350
>> [<ffffffff811715a0>] do_try_to_free_pages+0x170/0x530
>> [<ffffffff81171b76>] try_to_free_mem_cgroup_pages+0xb6/0x140
>> [<ffffffff811c6b5e>] __mem_cgroup_try_charge+0x1de/0xd70
>> [<ffffffff811c8c4b>] memcg_charge_kmem+0x9b/0x100
>> [<ffffffff811c8e1b>] __memcg_charge_slab+0x3b/0x90
>> [<ffffffff811b3664>] new_slab+0x264/0x3f0
>> [<ffffffff815e97c6>] __slab_alloc+0x315/0x48f
>> [<ffffffff811b49ac>] kmem_cache_alloc+0x1cc/0x210
>> [<ffffffff8115e4b5>] mempool_alloc_slab+0x15/0x20
>> [<ffffffff8115e5f9>] mempool_alloc+0x69/0x170
>> [<ffffffff8120bd42>] bvec_alloc+0x92/0x120
>> [<ffffffff8120bfb8>] bio_alloc_bioset+0x1e8/0x2e0
>> [<ffffffffa0072246>] ploop_make_request+0x2a6/0xac0 [ploop]
>> [<ffffffff81297172>] generic_make_request+0xe2/0x130
>> [<ffffffff81297237>] submit_bio+0x77/0x1c0
>> [<ffffffff8121341f>] do_mpage_readpage+0x37f/0x6e0
>> [<ffffffff8121386b>] mpage_readpages+0xeb/0x160
>> [<ffffffffa01a051c>] ext4_readpages+0x3c/0x40 [ext4]
>> [<ffffffff811683c0>] __do_page_cache_readahead+0x1e0/0x260
>> [<ffffffff81168b11>] ra_submit+0x21/0x30
>> [<ffffffff8115dea1>] filemap_fault+0x321/0x4b0
>> [<ffffffff811864ca>] __do_fault+0x8a/0x560
>> [<ffffffff8118b2d0>] handle_mm_fault+0x3d0/0xd80
>> [<ffffffff815f73ee>] __do_page_fault+0x15e/0x530
>> [<ffffffff815f77da>] do_page_fault+0x1a/0x70
>> [<ffffffff815f3a08>] page_fault+0x28/0x30
>>
>> https://jira.sw.ru/browse/PSBM-38842
>>
>> Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
>> ---
>>   drivers/block/ploop/dev.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
>> index 30eb8a7551e5..f37df4dacf8c 100644
>> --- a/drivers/block/ploop/dev.c
>> +++ b/drivers/block/ploop/dev.c
>> @@ -717,7 +717,7 @@ preallocate_bio(struct bio * orig_bio, struct ploop_device * plo)
>>       }
>>
>>       if (nbio == NULL)
>> -        nbio = bio_alloc(GFP_NOFS, max(orig_bio->bi_max_vecs, block_vecs(plo)));
>> +        nbio = bio_alloc(GFP_NOIO, max(orig_bio->bi_max_vecs, block_vecs(plo)));
>>       return nbio;
>>   }
>>
>> @@ -852,7 +852,7 @@ static void ploop_make_request(struct request_queue *q, struct bio *bio)
>>
>>       if (!current->io_context) {
>>           struct io_context *ioc;
>> -        ioc = get_task_io_context(current, GFP_NOFS, NUMA_NO_NODE);
>> +        ioc = get_task_io_context(current, GFP_NOIO, NUMA_NO_NODE);
>>           if (ioc)
>>               put_io_context(ioc);
>>       }
>>
> _______________________________________________
> Devel mailing list
> Devel at openvz.org
> https://lists.openvz.org/mailman/listinfo/devel
>