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Message-ID: <CA+G9fYvdzY+vWhPKPmyPDJNDqvH7AaU4HfKTFtgUwU+KTrD9_Q@mail.gmail.com>
Date: Thu, 3 Oct 2024 11:08:39 +0530
From: Naresh Kamboju <naresh.kamboju@...aro.org>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Kairui Song <kasong@...cent.com>, open list <linux-kernel@...r.kernel.org>,
lkft-triage@...ts.linaro.org, Linux Regressions <regressions@...ts.linux.dev>,
linux-mm <linux-mm@...ck.org>, Andrew Morton <akpm@...ux-foundation.org>,
Arnd Bergmann <arnd@...db.de>, Anders Roxell <anders.roxell@...aro.org>
Subject: Re: next-20241001: WARNING: at mm/list_lru.c:77 list_lru_del
(mm/list_lru.c:212 mm/list_lru.c:200)
On Wed, 2 Oct 2024 at 16:58, Dan Carpenter <dan.carpenter@...aro.org> wrote:
>
> On Wed, Oct 02, 2024 at 02:25:34PM +0300, Dan Carpenter wrote:
> > On Wed, Oct 02, 2024 at 02:24:20PM +0300, Dan Carpenter wrote:
> > > Let's add Kairui Song to the CC list.
> > >
> > > One simple thing is that we should add a READ_ONCE() to the comparison. Naresh,
> > > could you test the attached diff? I don't know that it will fix it but it's
> > > worth checking the easy stuff first.
> > >
> >
> > Actually that's not right. Let me write a different patch.
>
> Try this one.
>
Thanks for the patch,
I have applied this patch and testing is in progress.
>From last night the tests running in a loop did not find the reported warning.
> regards,
> dan carpenter
>
> diff --git a/mm/list_lru.c b/mm/list_lru.c
> index 79c2d21504a2..2c429578ed31 100644
> --- a/mm/list_lru.c
> +++ b/mm/list_lru.c
> @@ -65,6 +65,7 @@ lock_list_lru_of_memcg(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
> bool irq, bool skip_empty)
> {
> struct list_lru_one *l;
> + long nr_items;
> rcu_read_lock();
> again:
> l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
> @@ -73,8 +74,9 @@ lock_list_lru_of_memcg(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
> spin_lock_irq(&l->lock);
> else
> spin_lock(&l->lock);
> - if (likely(READ_ONCE(l->nr_items) != LONG_MIN)) {
> - WARN_ON(l->nr_items < 0);
> + nr_items = READ_ONCE(l->nr_items);
> + if (likely(nr_items != LONG_MIN)) {
> + WARN_ON(nr_items < 0);
> rcu_read_unlock();
> return l;
> }
- Naresh
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