From: Rune Kleveland <rune.kleveland@infomedia.dk>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Yu Zhao <yuzhao@google.com>, Alexey Gladkov <legion@kernel.org>,
Jordan Glover <Golden_Miller83@protonmail.ch>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, containers@lists.linux-foundation.org
Subject: Re: [CFT][PATCH] ucounts: Fix signal ucount refcounting
Date: Sun, 17 Oct 2021 18:47:27 +0200 [thread overview]
Message-ID: <24192747-7f69-ef22-7bf1-96b2e7c2bca1@infomedia.dk> (raw)
In-Reply-To: <87mtnavszx.fsf_-_@disp2133>
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.
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:[~2021-10-17 16:51 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 [this message]
2021-10-18 6:25 ` Yu Zhao
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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