From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Shijie Luo <luoshijie1@huawei.com>
Cc: linux-ext4@vger.kernel.org, jack@suse.cz, lutianxiong@huawei.com
Subject: Re: [PATCH] ext4: add cond_resched() to __ext4_find_entry()
Date: Wed, 19 Feb 2020 23:55:13 -0500 [thread overview]
Message-ID: <20200220045513.GD476845@mit.edu> (raw)
In-Reply-To: <20200215080206.13293-1-luoshijie1@huawei.com>
On Sat, Feb 15, 2020 at 03:02:06AM -0500, Shijie Luo wrote:
> We tested a soft lockup problem in linux 4.19 which could also
> be found in linux 5.x.
>
> When dir inode takes up a large number of blocks, and if the
> directory is growing when we are searching, it's possible the
> restart branch could be called many times, and the do while loop
> could hold cpu a long time.
>
> Here is the call trace in linux 4.19.
>
> [ 473.756186] Call trace:
> [ 473.756196] dump_backtrace+0x0/0x198
> [ 473.756199] show_stack+0x24/0x30
> [ 473.756205] dump_stack+0xa4/0xcc
> [ 473.756210] watchdog_timer_fn+0x300/0x3e8
> [ 473.756215] __hrtimer_run_queues+0x114/0x358
> [ 473.756217] hrtimer_interrupt+0x104/0x2d8
> [ 473.756222] arch_timer_handler_virt+0x38/0x58
> [ 473.756226] handle_percpu_devid_irq+0x90/0x248
> [ 473.756231] generic_handle_irq+0x34/0x50
> [ 473.756234] __handle_domain_irq+0x68/0xc0
> [ 473.756236] gic_handle_irq+0x6c/0x150
> [ 473.756238] el1_irq+0xb8/0x140
> [ 473.756286] ext4_es_lookup_extent+0xdc/0x258 [ext4]
> [ 473.756310] ext4_map_blocks+0x64/0x5c0 [ext4]
> [ 473.756333] ext4_getblk+0x6c/0x1d0 [ext4]
> [ 473.756356] ext4_bread_batch+0x7c/0x1f8 [ext4]
> [ 473.756379] ext4_find_entry+0x124/0x3f8 [ext4]
> [ 473.756402] ext4_lookup+0x8c/0x258 [ext4]
> [ 473.756407] __lookup_hash+0x8c/0xe8
> [ 473.756411] filename_create+0xa0/0x170
> [ 473.756413] do_mkdirat+0x6c/0x140
> [ 473.756415] __arm64_sys_mkdirat+0x28/0x38
> [ 473.756419] el0_svc_common+0x78/0x130
> [ 473.756421] el0_svc_handler+0x38/0x78
> [ 473.756423] el0_svc+0x8/0xc
> [ 485.755156] watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [tmp:5149]
>
> Add cond_resched() to avoid soft lockup and to provide a better
> system responding.
>
> Signed-off-by: Shijie Luo <luoshijie1@huawei.com>
Thanks, applied.
- Ted
prev parent reply other threads:[~2020-02-20 4:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-15 8:02 [PATCH] ext4: add cond_resched() to __ext4_find_entry() Shijie Luo
2020-02-17 10:31 ` Jan Kara
2020-02-20 4:55 ` Theodore Y. Ts'o [this message]
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