linux-kernel - Re: [jet.chen@...el.com: [bio] kernel BUG at drivers/block/virtio

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: <CACVXFVOaF-EOioE38sy9=2f-+rKECJnzUCSHrL-VZJi1Ycj_wA@mail.gmail.com>
Date:	Tue, 27 May 2014 12:03:29 +0800
From:	Ming Lei <tom.leiming@...il.com>
To:	Maurizio Lombardi <mlombard@...hat.com>
Cc:	Jens Axboe <axboe@...nel.dk>, jet.chen@...el.com,
	Stephen Rothwell <sfr@...b.auug.org.au>,
	LKML <linux-kernel@...r.kernel.org>, lkp@...org,
	Fengguang Wu <fengguang.wu@...el.com>
Subject: Re: [jet.chen@...el.com: [bio] kernel BUG at drivers/block/virtio_blk.c:166!]

On Tue, May 27, 2014 at 3:43 AM, Maurizio Lombardi <mlombard@...hat.com> wrote:
> Hi Jens,
>
> looks like that commit 3979ef4dcf3d1de55a560a3a4016c30a835df44d ("bio-modify-__bio_add_page-to-accept-pages-that-dont-start-a-new-segment-v3")
> introduces a regression, as reported by Jet Chan.
>
> Do you have any idea about the possible problem with this patch?
>
> it is the one that performs a recount of the segments in case of failure in __bio_add_page()
>
> http://www.spinics.net/lists/mm-commits/msg103684.html
>
> I would not be surprised if the bug was introduced by fceb38f36f, because it
> contained a mystake that commit 3979ef4dcf supposedly fixed.
> But learning that commit 3979ef4dcf is introducing a regression leaves
> me quite puzzled.

>From code of __blk_recalc_rq_segments(), looks it
won't check if recounted physical segment number is
bigger than queue_max_segments(), so wondering if
blk_recount_segments() can always decrease
physical segment number.

Thanks,
--
Ming Lei
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/