From: Peter Zijlstra <peterz@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>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH 4/4] mm: Do periodic rescheduling when freeing objects in kmem_free_up_q()
Date: Thu, 21 Mar 2019 23:00:35 +0100 [thread overview]
Message-ID: <20190321220035.GF7905@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20190321214512.11524-5-longman@redhat.com>
On Thu, Mar 21, 2019 at 05:45:12PM -0400, Waiman Long wrote:
> If the freeing queue has many objects, freeing all of them consecutively
> may cause soft lockup especially on a debug kernel. So kmem_free_up_q()
> is modified to call cond_resched() if running in the process context.
>
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
> mm/slab_common.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index dba20b4208f1..633a1d0f6d20 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1622,11 +1622,14 @@ EXPORT_SYMBOL_GPL(kmem_free_q_add);
> * kmem_free_up_q - free all the objects in the freeing queue
> * @head: freeing queue head
> *
> - * Free all the objects in the freeing queue.
> + * Free all the objects in the freeing queue. The caller cannot hold any
> + * non-sleeping locks.
> */
> void kmem_free_up_q(struct kmem_free_q_head *head)
> {
> struct kmem_free_q_node *node, *next;
> + bool do_resched = !in_irq();
> + int cnt = 0;
>
> for (node = head->first; node; node = next) {
> next = node->next;
> @@ -1634,6 +1637,12 @@ void kmem_free_up_q(struct kmem_free_q_head *head)
> kmem_cache_free(node->cachep, node);
> else
> kfree(node);
> + /*
> + * Call cond_resched() every 256 objects freed when in
> + * process context.
> + */
> + if (do_resched && !(++cnt & 0xff))
> + cond_resched();
Why not just: cond_resched() ?
> }
> }
> EXPORT_SYMBOL_GPL(kmem_free_up_q);
> --
> 2.18.1
>
next prev parent reply other threads:[~2019-03-21 22:00 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 [this message]
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
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