From: Oleg Nesterov <oleg@redhat.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Waiman Long <longman@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
selinux@vger.kernel.org, Paul Moore <paul@paul-moore.com>,
Stephen Smalley <sds@tycho.nsa.gov>,
Eric Paris <eparis@parisplace.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: Re: [PATCH 0/4] Signal: Fix hard lockup problem in flush_sigqueue()
Date: Fri, 22 Mar 2019 12:49:17 +0100 [thread overview]
Message-ID: <20190322114917.GC28876@redhat.com> (raw)
In-Reply-To: <20190322101535.GA10344@bombadil.infradead.org>
On 03/22, Matthew Wilcox wrote:
>
> On Thu, Mar 21, 2019 at 05:45:08PM -0400, Waiman Long wrote:
> > It was found that if a process has accumulated sufficient number of
> > pending signals, the exiting of that process may cause its parent to
> > have hard lockup when running on a debug kernel with a slow memory
> > freeing path (like with KASAN enabled).
>
> I appreciate these are "reliable" signals, but why do we accumulate so
> many signals to a task which will never receive them? Can we detect at
> signal delivery time that the task is going to die and avoid queueing
> them in the first place?
A task can block the signal and accumulate up to RLIMIT_SIGPENDING signals,
then it can exit.
Oleg.
prev parent reply other threads:[~2019-03-22 11:49 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-21 21:45 [PATCH 0/4] Signal: Fix hard lockup problem in flush_sigqueue() Waiman Long
2019-03-21 21:45 ` [PATCH 1/4] mm: Implement kmem objects freeing queue Waiman Long
2019-03-22 17:47 ` Christopher Lameter
2019-03-21 21:45 ` [PATCH 2/4] signal: Make flush_sigqueue() use free_q to release memory Waiman Long
2019-03-22 1:52 ` Matthew Wilcox
2019-03-22 11:16 ` Oleg Nesterov
2019-03-22 16:10 ` Waiman Long
2019-03-22 17:50 ` Christopher Lameter
2019-03-22 18:12 ` Waiman Long
2019-03-22 19:39 ` Christopher Lameter
2019-03-22 19:59 ` Matthew Wilcox
2019-03-25 14:15 ` Christopher Lameter
2019-03-25 15:26 ` Matthew Wilcox
2019-03-25 16:16 ` Christopher Lameter
2019-03-26 13:36 ` Oleg Nesterov
2019-03-26 13:29 ` Oleg Nesterov
2019-03-21 21:45 ` [PATCH 3/4] signal: Add free_uid_to_q() Waiman Long
2019-03-21 21:45 ` [PATCH 4/4] mm: Do periodic rescheduling when freeing objects in kmem_free_up_q() Waiman Long
2019-03-21 22:00 ` Peter Zijlstra
2019-03-22 14:35 ` Waiman Long
2019-03-22 10:15 ` [PATCH 0/4] Signal: Fix hard lockup problem in flush_sigqueue() Matthew Wilcox
2019-03-22 11:49 ` Oleg Nesterov [this message]
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