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]
Date: Tue, 12 Mar 2024 14:11:24 -0700
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Jakub Kicinski <kuba@...nel.org>, Jens Axboe <axboe@...nel.dk>, 
	Johannes Thumshirn <johannes.thumshirn@....com>
Cc: davem@...emloft.net, netdev@...r.kernel.org, linux-kernel@...r.kernel.org, 
	pabeni@...hat.com, bpf@...r.kernel.org, Tejun Heo <tj@...nel.org>
Subject: Re: [GIT PULL] Networking for v6.9

On Tue, 12 Mar 2024 at 13:47, Jakub Kicinski <kuba@...nel.org> wrote:
>
> With your tree as of 65d287c7eb1d it gets to prompt but dies soon after
> when prod services kick in (dunno what rpm Kdump does but says iocost
> so adding Tejun):

Both of your traces are timers that seem to either lock up in ioc_now():

   https://lore.kernel.org/all/20240312133427.1a744844@kernel.org/

and now it looks like ioc_timer_fn():

  https://lore.kernel.org/all/20240312134739.248e6bd3@kernel.org/

But in neither case does it actually look like it's a lockup on a *lock*.

IOW, the NMI isn't happening on some spin_lock sequence or anything like that.

Yes, ioc_now() could have been looping on the seq read-lock if the
sequence number was odd. But the writers do seem to be done with
interrupts disabled, plus then you wouldn't have this lockup in
ioc_timer_fn, so it's probably not that.

And yes, ioc_timer_fn() does take locks, but again, that doesn't seem
to be where it is hanging.

So it smells like it's an endless loop in ioc_timer_fn() to me, or
perhaps retriggering the timer itself infinitely.

Which would then explain both of those traces (that endless loop would
call ioc_now() as part of it).

The blk-iocost.c code itself hasn't changed, but the timer code has
gone through big changes.

That said, there's a more blk-related change: da4c8c3d0975 ("block:
cache current nsec time in struct blk_plug").

*And* your second dump is from that

        period_vtime = now.vnow - ioc->period_at_vtime;
        if (WARN_ON_ONCE(!period_vtime)) {

so it smells like the blk-iocost code is just completely confused by
the time caching. Jens?

Jakub, it might be worth seeing if just reverting that commit
da4c8c3d0975 makes the problem go away. Otherwise a bisect might be
needed...

          Linus

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ