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From: Jordan Glover <Golden_Miller83@protonmail.ch>
To: Yu Zhao <yuzhao@google.com>
Cc: Rune Kleveland <rune.kleveland@infomedia.dk>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	Alexey Gladkov <legion@kernel.org>,
	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 10:31:45 +0000	[thread overview]
Message-ID: <yDKmqVctE8MV6p62Ru2cNDTwa7XtEl9B_lMj4xabNKfbwR2A_aLWNvYpepdZBTbDZDJtMdTZtsdWLfp6SIRksWwfCOV6jJ1UuBRbLSsBxiI=@protonmail.ch> (raw)
In-Reply-To: <CAOUHufZJFAK3uBma0kgEjb7YK6Fq4vQqdGNFz6_=QkFBbqGBCw@mail.gmail.com>

On Monday, October 18th, 2021 at 6:25 AM, Yu Zhao <yuzhao@google.com> wrote:

> 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.
>

I'm also unable to reproduce the crash as for now. Thx for the patch.

Jordan

> > 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.

  reply	other threads:[~2021-10-18 10:31 UTC|newest]

Thread overview: 73+ 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 19:49 ` Jordan Glover
2021-09-15 21:02 ` Eric W. Biederman
2021-09-15 21:02   ` Eric W. Biederman
2021-09-15 22:42   ` Jordan Glover
2021-09-15 22:42     ` Jordan Glover
2021-09-15 23:44     ` Yu Zhao
2021-09-15 23:44       ` Yu Zhao
2021-09-17 16:15       ` Eric W. Biederman
2021-09-17 16:15         ` Eric W. Biederman
2021-09-17 18:45         ` Yu Zhao
2021-09-17 18:45           ` Yu Zhao
2021-09-15 23:47     ` Jordan Glover
2021-09-15 23:47       ` Jordan Glover
2021-09-16 17:30       ` Eric W. Biederman
2021-09-16 17:30         ` Eric W. Biederman
2021-09-16 19:14         ` Alexey Gladkov
2021-09-16 19:14           ` Alexey Gladkov
2021-09-28 13:40         ` Jordan Glover
2021-09-28 13:40           ` Jordan Glover
2021-09-29 17:36           ` Alexey Gladkov
2021-09-29 17:36             ` Alexey Gladkov
2021-09-29 21:39             ` Jordan Glover
2021-09-29 21:39               ` Jordan Glover
2021-09-30 13:06               ` Alexey Gladkov
2021-09-30 22:27                 ` Yu Zhao
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
2021-10-06  7:57                       ` Rune Kleveland
2021-10-10  8:59                       ` Rune Kleveland
2021-10-11 13:09                         ` Hillf Danton
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
2021-10-16  2:08                           ` Hillf Danton
2021-10-16 18:00                             ` Eric W. Biederman
2021-10-17 16:47                           ` Rune Kleveland
2021-10-18  6:25                             ` Yu Zhao
2021-10-18 10:31                               ` Jordan Glover [this message]
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
2021-10-24 17:36                                 ` kernel test robot
2021-10-25 14:13                                   ` Eric W. Biederman
2021-11-06  5:05                                 ` kernel test robot
2021-11-06  5:05                                   ` kernel test robot
2021-11-06 20:22                                 ` kernel test robot
2021-11-06 20:22                                   ` kernel test robot
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
2021-10-11 13:39                       ` linux 5.14.3: free_user_ns causes NULL pointer dereference Alexey Gladkov
2021-10-06  2:12                   ` Hillf Danton
2021-10-06  6:22                     ` Yu Zhao
2021-10-07 13:28                     ` Jordan Glover
2021-10-10 11:26                       ` Hillf Danton
2021-10-03 19:37             ` Jordan Glover
2021-10-03 19:37               ` Jordan Glover
2021-10-17 13:36 [CFT][PATCH] ucounts: Fix signal ucount refcounting kernel test robot
2021-11-26 15:09 kernel test robot
2021-11-27  1:35 kernel test robot

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