From: Al Viro <viro@zeniv.linux.org.uk>
To: "zhengbin (A)" <zhengbin13@huawei.com>
Cc: jack@suse.cz, akpm@linux-foundation.org,
linux-fsdevel@vger.kernel.org,
"zhangyi (F)" <yi.zhang@huawei.com>,
renxudong1@huawei.com, Hou Tao <houtao1@huawei.com>
Subject: Re: Possible FS race condition between iterate_dir and d_alloc_parallel
Date: Mon, 9 Sep 2019 15:59:10 +0100 [thread overview]
Message-ID: <20190909145910.GG1131@ZenIV.linux.org.uk> (raw)
In-Reply-To: <afdfa1f4-c954-486b-1eb2-efea6fcc2e65@huawei.com>
On Mon, Sep 09, 2019 at 10:10:00PM +0800, zhengbin (A) wrote:
Hmm... So your theory is that what you are seeing is the insertion
into the list done by list_add() exposing an earlier ->next pointer
to those who might be doing lockless walk through the list.
Potentially up to the last barrier done before the list_add()...
> We can solute it in 2 ways:
>
> 1. add a smp_wmb between __d_alloc and list_add(&dentry->d_child, &parent->d_subdirs)
> 2. revert commit ebaaa80e8f20 ("lockless next_positive()")
I want to take another look at the ->d_subdirs/->d_child readers...
I agree that the above sounds plausible, but I really want to be
sure about the exclusion we have for those accesses.
I'm not sure that smp_wmb() alone would suffice, BTW - the reader side
loop would need to be careful as well.
Which architecture it was, again? arm64?
next prev parent reply other threads:[~2019-09-09 14:59 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-03 14:44 Possible FS race condition between iterate_dir and d_alloc_parallel zhengbin (A)
2019-09-03 15:40 ` Al Viro
2019-09-03 15:41 ` Al Viro
2019-09-04 6:15 ` zhengbin (A)
2019-09-05 17:47 ` Al Viro
2019-09-06 0:55 ` Jun Li
2019-09-06 2:00 ` Al Viro
2019-09-06 2:32 ` zhengbin (A)
2019-09-09 14:10 ` zhengbin (A)
2019-09-09 14:59 ` Al Viro [this message]
2019-09-09 15:10 ` zhengbin (A)
[not found] ` <7e32cda5-dc89-719d-9651-cf2bd06ae728@huawei.com>
2019-09-10 21:53 ` Al Viro
2019-09-10 22:17 ` Al Viro
2019-09-14 16:16 ` [PATCH] " Al Viro
2019-09-14 16:49 ` Linus Torvalds
2019-09-14 17:01 ` Al Viro
2019-09-14 17:15 ` Linus Torvalds
2019-09-14 20:04 ` Al Viro
2019-09-14 22:57 ` Linus Torvalds
2019-09-15 0:50 ` Al Viro
2019-09-15 1:41 ` Linus Torvalds
2019-09-15 16:02 ` Al Viro
2019-09-15 17:58 ` Linus Torvalds
2019-09-21 14:07 ` Al Viro
2019-09-21 16:21 ` Linus Torvalds
2019-09-21 17:18 ` Al Viro
2019-09-21 17:38 ` Linus Torvalds
2019-09-24 2:52 ` Al Viro
2019-09-24 13:30 ` Josef Bacik
2019-09-24 14:51 ` Al Viro
2019-09-24 15:01 ` Josef Bacik
2019-09-24 15:11 ` Al Viro
2019-09-24 15:26 ` Josef Bacik
2019-09-24 16:33 ` Al Viro
[not found] ` <CAHk-=wiJ1eY7y6r_cFNRPCqD+BJZS7eJeQFO6OrXxRFjDAipsQ@mail.gmail.com>
2019-09-29 5:29 ` Al Viro
2019-09-25 11:59 ` Amir Goldstein
2019-09-25 12:22 ` Al Viro
2019-09-25 12:34 ` Amir Goldstein
2019-09-22 21:29 ` Al Viro
2019-09-23 3:32 ` zhengbin (A)
2019-09-23 5:08 ` Al Viro
2019-09-16 2:04 ` 266a9a8b41: WARNING:possible_recursive_locking_detected kernel test robot
2019-09-16 2:58 ` Al Viro
2019-09-16 2:58 ` Al Viro
2019-09-16 3:03 ` Al Viro
2019-09-16 3:03 ` Al Viro
2019-09-16 3:44 ` Linus Torvalds
2019-09-16 3:44 ` Linus Torvalds
2019-09-16 17:16 ` Al Viro
2019-09-16 17:16 ` Al Viro
2019-09-16 17:29 ` Al Viro
2019-09-16 17:29 ` Al Viro
2019-09-17 8:59 ` Rong Chen
2019-09-17 7:03 ` zhengbin
2019-09-17 12:01 ` Al Viro
2019-09-17 12:01 ` Al Viro
2019-09-19 3:36 ` zhengbin
2019-09-19 3:36 ` zhengbin (A)
2019-09-19 3:55 ` Al Viro
2019-09-19 3:55 ` Al Viro
2019-09-19 4:16 ` zhengbin
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