From: Linus Torvalds <torvalds@linux-foundation.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>, Michal Hocko <mhocko@kernel.org>,
Linux-MM <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [RFC PATCH] mm: silence soft lockups from unlock_page
Date: Thu, 23 Jul 2020 13:03:28 -0700 [thread overview]
Message-ID: <CAHk-=whQK3OGwExTzCrwwvuuVaQAgs8KsR-Yv8m1BmXoNZZ=jQ@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wgyc7en4=HddEYiz_RKJXfqe1JYv3BzHc=+_wYq9ti+LQ@mail.gmail.com>
On Thu, Jul 23, 2020 at 10:32 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So here's a v2, now as a "real" commit with a commit message and everything.
Oh, except it's broken.
Switching from the "am I still on the list" logic to the
"WQ_FLAG_WOKEN is set if woken" logic was all well and good, but I
missed the case where we did that trylock_page_bit_common().
It used to just not add the thing to the list if it would get the page
bit, and then the rest of the waiting logic looked at that and was
happy.
But now if it needs to actually fake that WQ_FLAG_WOKEN flag.
So that patch needs to do something like this:
if (!trylock_page_bit_common(page, bit_nr, behavior))
__add_wait_queue_entry_tail(q, wait);
else
wait->flags |= WQ_FLAG_WOKEN;
in there. Or maybe have that bit set originally, and clear it when we
add to the wait queue.
I'll send a new version after I actually test it.
Linus
next prev parent reply other threads:[~2020-07-23 20:03 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-21 6:32 [RFC PATCH] mm: silence soft lockups from unlock_page Michal Hocko
2020-07-21 11:10 ` Qian Cai
2020-07-21 11:25 ` Michal Hocko
2020-07-21 11:44 ` Qian Cai
2020-07-21 12:17 ` Michal Hocko
2020-07-21 13:23 ` Qian Cai
2020-07-21 13:38 ` Michal Hocko
2020-07-21 14:15 ` Qian Cai
2020-07-21 14:17 ` Chris Down
2020-07-21 15:00 ` Michal Hocko
2020-07-21 15:33 ` Linus Torvalds
2020-07-21 15:49 ` Michal Hocko
2020-07-22 18:29 ` Linus Torvalds
2020-07-22 21:29 ` Hugh Dickins
2020-07-22 22:10 ` Linus Torvalds
2020-07-22 23:42 ` Linus Torvalds
2020-07-23 0:23 ` Linus Torvalds
2020-07-23 12:47 ` Oleg Nesterov
2020-07-23 17:32 ` Linus Torvalds
2020-07-23 18:01 ` Oleg Nesterov
2020-07-23 18:22 ` Linus Torvalds
2020-07-23 19:03 ` Linus Torvalds
2020-07-24 14:45 ` Oleg Nesterov
2020-07-23 20:03 ` Linus Torvalds [this message]
2020-07-23 23:11 ` Hugh Dickins
2020-07-23 23:43 ` Linus Torvalds
2020-07-24 0:07 ` Hugh Dickins
2020-07-24 0:46 ` Linus Torvalds
2020-07-24 3:45 ` Hugh Dickins
2020-07-24 15:24 ` Oleg Nesterov
2020-07-24 17:32 ` Linus Torvalds
2020-07-24 23:25 ` Linus Torvalds
2020-07-25 2:08 ` Hugh Dickins
2020-07-25 2:46 ` Linus Torvalds
2020-07-25 10:14 ` Oleg Nesterov
2020-07-25 18:48 ` Linus Torvalds
2020-07-25 19:27 ` Oleg Nesterov
2020-07-25 19:51 ` Linus Torvalds
2020-07-26 13:57 ` Oleg Nesterov
2020-07-25 21:19 ` Hugh Dickins
2020-07-26 4:22 ` Hugh Dickins
2020-07-26 20:30 ` Hugh Dickins
2020-07-26 20:41 ` Linus Torvalds
2020-07-26 22:09 ` Hugh Dickins
2020-07-27 19:35 ` Greg KH
2020-08-06 5:46 ` Hugh Dickins
2020-08-18 13:50 ` Greg KH
2020-08-06 5:21 ` Hugh Dickins
2020-08-06 17:07 ` Linus Torvalds
2020-08-06 18:00 ` Matthew Wilcox
2020-08-06 18:32 ` Linus Torvalds
2020-08-07 18:41 ` Hugh Dickins
2020-08-07 19:07 ` Linus Torvalds
2020-08-07 19:35 ` Matthew Wilcox
2020-08-03 13:14 ` Michal Hocko
2020-08-03 17:56 ` Linus Torvalds
2020-07-25 9:39 ` Oleg Nesterov
2020-07-23 8:03 ` Michal Hocko
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