On Fri 15-09-17 17:58:49, wang Yu wrote:
> From: "yuwang.yuwang" <yuwang.yuwang@xxxxxxxxxxxxxxx>
>
> I found a softlockup when running some stress testcase in 4.9.x,
> but i think the mainline have the same problem.
>
> call trace:
> [365724.502896] NMI watchdog: BUG: soft lockup - CPU#31 stuck for 22s!
> [jbd2/sda3-8:1164]
> ...
> ...
> [365724.503258] Call Trace:
> [365724.503260] [<ffffffff811ace5f>] warn_alloc+0x13f/0x170
> [365724.503264] [<ffffffff811ad8c2>] __alloc_pages_slowpath+0x9b2/0xc10
> [365724.503265] [<ffffffff811add43>] __alloc_pages_nodemask+0x223/0x2a0
> [365724.503268] [<ffffffff811fe838>] alloc_pages_current+0x88/0x120
> [365724.503270] [<ffffffff811a3644>] __page_cache_alloc+0xb4/0xc0
> [365724.503272] [<ffffffff811a49e9>] pagecache_get_page+0x59/0x230
> [365724.503275] [<ffffffff8126b2db>] __getblk_gfp+0xfb/0x2f0
> [365724.503281] [<ffffffffa00f9cee>]
> jbd2_journal_get_descriptor_buffer+0x5e/0xe0 [jbd2]
> [365724.503286] [<ffffffffa00f2a01>]
> jbd2_journal_commit_transaction+0x901/0x1880 [jbd2]
> [365724.503291] [<ffffffff8102d6a5>] ? __switch_to+0x215/0x730
> [365724.503294] [<ffffffff810f962d>] ? lock_timer_base+0x7d/0xa0
> [365724.503298] [<ffffffffa00f7cda>] kjournald2+0xca/0x260 [jbd2]
> [365724.503300] [<ffffffff810cfb00>] ? prepare_to_wait_event+0xf0/0xf0
> [365724.503304] [<ffffffffa00f7c10>] ? commit_timeout+0x10/0x10 [jbd2]
> [365724.503307] [<ffffffff810a8d66>] kthread+0xe6/0x100
> [365724.503309] [<ffffffff810a8c80>] ? kthread_park+0x60/0x60
> [365724.503313] [<ffffffff816f3795>] ret_from_fork+0x25/0x30
>
> we can limit the warn_alloc caller to workaround it.
> __alloc_pages_slowpath only call once warn_alloc each time.
similar attempts to add a lock there were tried in the past and refused.
Anyway using a normal lock would be preferred over a bit lock. But the
most important part is to identify _why_ we see the lockup trigerring in
the first place. And try to fix it rather than workaround it here.
> Signed-off-by: yuwang.yuwang <yuwang.yuwang@xxxxxxxxxxxxxxx>
> Suggested-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> ---
> mm/page_alloc.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 2abf8d5..8b86686 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3525,6 +3525,7 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
> unsigned long alloc_start = jiffies;
> unsigned int stall_timeout = 10 * HZ;
> unsigned int cpuset_mems_cookie;
> + static unsigned long stall_warn_lock;
>
> /*
> * In the slowpath, we sanity check order to avoid ever trying to
> @@ -3698,11 +3699,13 @@ bool gfp_pfmemalloc_allowed(gfp_t gfp_mask)
> goto nopage;
>
> /* Make sure we know about allocations which stall for too long */
> - if (time_after(jiffies, alloc_start + stall_timeout)) {
> + if (time_after(jiffies, alloc_start + stall_timeout) &&
> + !test_and_set_bit_lock(0, &stall_warn_lock)) {
> warn_alloc(gfp_mask,
> "page allocation stalls for %ums, order:%u",
> jiffies_to_msecs(jiffies-alloc_start), order);
> - stall_timeout += 10 * HZ;
> + stall_timeout = jiffies - alloc_start + 10 * HZ;
> + clear_bit_unlock(0, &stall_warn_lock);
> }
>
> if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,
> --
> 1.8.3.1
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
