From: Yu Zhao <yuzhao@google.com>
To: Rune Kleveland <rune.kleveland@infomedia.dk>,
"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Gladkov <legion@kernel.org>,
Jordan Glover <Golden_Miller83@protonmail.ch>,
LKML <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
"containers\\@lists.linux-foundation.org"
<containers@lists.linux-foundation.org>
Subject: Re: [CFT][PATCH] ucounts: Fix signal ucount refcounting
Date: Mon, 18 Oct 2021 00:25:54 -0600 [thread overview]
Message-ID: <CAOUHufZJFAK3uBma0kgEjb7YK6Fq4vQqdGNFz6_=QkFBbqGBCw@mail.gmail.com> (raw)
In-Reply-To: <24192747-7f69-ef22-7bf1-96b2e7c2bca1@infomedia.dk>
On Sun, Oct 17, 2021 at 10:47 AM Rune Kleveland
<rune.kleveland@infomedia.dk> wrote:
>
> Hi!
>
> After applying the below patch, the 5 most problematic servers have run
> without any issues for 23 hours. That never happened before the patch on
> 5.14, so the patch seems to have fixed the issue for me.
Confirm. I couldn't reproduce the problem on 5.14 either.
> On Monday there will be more load on the servers, which caused them to
> crash faster without the patch. I will let you know if it happens again.
>
> Best regards,
> Rune
>
> On 16/10/2021 00:10, Eric W. Biederman wrote:
> >
> > In commit fda31c50292a ("signal: avoid double atomic counter
> > increments for user accounting") Linus made a clever optimization to
> > how rlimits and the struct user_struct. Unfortunately that
> > optimization does not work in the obvious way when moved to nested
> > rlimits. The problem is that the last decrement of the per user
> > namespace per user sigpending counter might also be the last decrement
> > of the sigpending counter in the parent user namespace as well. Which
> > means that simply freeing the leaf ucount in __free_sigqueue is not
> > enough.
> >
> > Maintain the optimization and handle the tricky cases by introducing
> > inc_rlimit_get_ucounts and dec_rlimit_put_ucounts.
> >
> > By moving the entire optimization into functions that perform all of
> > the work it becomes possible to ensure that every level is handled
> > properly.
> >
> > I wish we had a single user across all of the threads whose rlimit
> > could be charged so we did not need this complexity.
next prev parent reply other threads:[~2021-10-18 6:26 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-15 19:49 linux 5.14.3: free_user_ns causes NULL pointer dereference Jordan Glover
2021-09-15 21:02 ` Eric W. Biederman
2021-09-15 22:42 ` Jordan Glover
2021-09-15 23:44 ` Yu Zhao
2021-09-17 16:15 ` Eric W. Biederman
2021-09-17 18:45 ` Yu Zhao
2021-09-15 23:47 ` Jordan Glover
2021-09-16 17:30 ` Eric W. Biederman
2021-09-16 19:14 ` Alexey Gladkov
2021-09-28 13:40 ` Jordan Glover
2021-09-29 17:36 ` Alexey Gladkov
2021-09-29 21:39 ` Jordan Glover
2021-09-30 13:06 ` Alexey Gladkov
2021-09-30 22:27 ` Yu Zhao
2021-10-04 17:10 ` Eric W. Biederman
2021-10-04 17:19 ` Eric W. Biederman
2021-10-04 21:34 ` Yu Zhao
2021-10-11 13:39 ` Alexey Gladkov
[not found] ` <ccbccf82-dc50-00b2-1cfd-3da5e2c81dbf@infomedia.dk>
2021-10-12 17:31 ` Eric W. Biederman
2021-10-15 22:10 ` [CFT][PATCH] ucounts: Fix signal ucount refcounting Eric W. Biederman
2021-10-15 23:09 ` Alexey Gladkov
2021-10-16 17:34 ` Eric W. Biederman
2021-10-17 19:35 ` Yu Zhao
2021-10-18 15:35 ` Eric W. Biederman
2021-10-17 16:47 ` Rune Kleveland
2021-10-18 6:25 ` Yu Zhao [this message]
2021-10-18 10:31 ` Jordan Glover
2021-10-18 16:06 ` [PATCH v2] " Eric W. Biederman
2021-10-18 17:21 ` [PATCH 0/3] ucounts: misc fixes Eric W. Biederman
2021-10-18 17:23 ` [PATCH 1/3] ucounts: Pair inc_rlimit_ucounts with dec_rlimit_ucoutns in commit_creds Eric W. Biederman
2021-10-18 17:23 ` [PATCH 2/3] ucounts: Proper error handling in set_cred_ucounts Eric W. Biederman
2021-10-18 17:24 ` [PATCH 3/3] ucounts: Move get_ucounts from cred_alloc_blank to key_change_session_keyring Eric W. Biederman
2021-10-18 17:54 ` [PATCH 0/4] ucounts: misc cleanups Eric W. Biederman
2021-10-18 17:55 ` [PATCH 1/4] ucounts: In set_cred_ucounts assume new->ucounts is non-NULL Eric W. Biederman
2021-10-18 17:56 ` [PATCH 2/4] ucounts: Remove unnecessary test for NULL ucount in get_ucounts Eric W. Biederman
2021-10-18 17:56 ` [PATCH 3/4] ucounts: Add get_ucounts_or_wrap for clarity Eric W. Biederman
2021-10-18 17:57 ` [PATCH 4/4] ucounts: Use atomic_long_sub_return " Eric W. Biederman
2021-10-18 22:29 ` [PATCH 0/4] ucounts: misc cleanups Yu Zhao
2021-10-18 22:28 ` [PATCH 0/3] ucounts: misc fixes Yu Zhao
2021-10-18 22:26 ` [PATCH v2] ucounts: Fix signal ucount refcounting Yu Zhao
[not found] ` <20211016020833.1538-1-hdanton@sina.com>
2021-10-16 18:00 ` [CFT][PATCH] " Eric W. Biederman
[not found] ` <20211006021219.2010-1-hdanton@sina.com>
2021-10-06 6:22 ` linux 5.14.3: free_user_ns causes NULL pointer dereference Yu Zhao
2021-10-07 13:28 ` Jordan Glover
2021-10-03 19:37 ` Jordan Glover
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