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From: Matthew Wilcox <willy@infradead.org>
To: Waiman Long <longman@redhat.com>
Cc: 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>,
	Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 0/4] Signal: Fix hard lockup problem in flush_sigqueue()
Date: Fri, 22 Mar 2019 03:15:35 -0700	[thread overview]
Message-ID: <20190322101535.GA10344@bombadil.infradead.org> (raw)
In-Reply-To: <20190321214512.11524-1-longman@redhat.com>

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?

  parent reply	other threads:[~2019-03-22 10:16 UTC|newest]

Thread overview: 27+ 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
2019-03-22 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 17:50           ` Christopher Lameter
2019-03-22 18:12           ` Waiman Long
2019-03-22 19:39             ` Christopher Lameter
2019-03-22 19:39               ` Christopher Lameter
2019-03-22 19:59               ` Matthew Wilcox
2019-03-25 14:15                 ` Christopher Lameter
2019-03-25 14:15                   ` Christopher Lameter
2019-03-25 15:26                   ` Matthew Wilcox
2019-03-25 16:16                     ` Christopher Lameter
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 ` Matthew Wilcox [this message]
2019-03-22 11:49   ` [PATCH 0/4] Signal: Fix hard lockup problem in flush_sigqueue() Oleg Nesterov

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