linux-kernel - Re: [PATCH] blk-mq: use mutex_trylock to avoid lock inversion

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <2409013d789ca266879d24c815b76c2193e23fe3.camel@wdc.com>
Date:   Tue, 19 Jun 2018 15:20:39 +0000
From:   Bart Van Assche <Bart.VanAssche@....com>
To:     "jianchao.w.wang@...cle.com" <jianchao.w.wang@...cle.com>,
        "axboe@...nel.dk" <axboe@...nel.dk>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>
Subject: Re: [PATCH] blk-mq: use mutex_trylock to avoid lock inversion

On Tue, 2018-06-19 at 15:00 +0800, Jianchao Wang wrote:
> Currently, the kobject_del for kobjs of mq, hctx and ctx is invoked
> under sysfs_lock, lock inversion will come up when other one is
> acessing the associated sysfs file and trying to acquire the
> sysfs_lock. To fix it, use mutex_trylock in blk_mq_sysfs_ops and
> blk_mq_hw_sysfs_ops, if the lock in on contending, return -EAGAIN.

Is this a theoretical issue or something you actually ran into? Which lock
other than sysfs_lock do you think is involved in the lock inversion?

Bart.