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: <e97a0603-f9e3-1b00-4a09-c569d4f73d7b@acm.org>
Date:   Mon, 21 Dec 2020 18:13:01 -0800
From:   Bart Van Assche <bvanassche@....org>
To:     John Garry <john.garry@...wei.com>, axboe@...nel.dk,
        ming.lei@...hat.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        hch@....de, hare@...e.de, ppvk@...eaurora.org,
        kashyap.desai@...adcom.com, linuxarm@...wei.com
Subject: Re: [RFC PATCH v2 2/2] blk-mq: Lockout tagset iter when freeing rqs

On 12/21/20 10:47 AM, John Garry wrote:
> Yes, I agree, and I'm not sure what I wrote to give that impression.
> 
> About "root partition", above, I'm just saying that / is mounted on a
> sda partition:
> 
> root@...ntu:/home/john# mount | grep sda
> /dev/sda2 on / type ext4 (rw,relatime,errors=remount-ro,stripe=32)
> /dev/sda1 on /boot/efi type vfat
> (rw,relatime,fmask=0077,dmask=0077,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)

Hi John,

Thanks for the clarification. I want to take back my suggestion about
adding rcu_read_lock() / rcu_read_unlock() in blk_mq_tagset_busy_iter()
since it is not allowed to sleep inside an RCU read-side critical
section, since blk_mq_tagset_busy_iter() is used in request timeout
handling and since there may be blk_mq_ops.timeout implementations that
sleep.

Ming's suggestion to serialize blk_mq_tagset_busy_iter() and
blk_mq_free_rqs() looks interesting to me.

Thanks,

Bart.

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ