From: Al Viro <viro@zeniv.linux.org.uk>
To: Lucas Karpinski <lkarpins@redhat.com>
Cc: brauner@kernel.org, jack@suse.cz, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, alexl@redhat.com,
echanude@redhat.com, ikent@redhat.com
Subject: Re: [RFC v2 1/1] fs/namespace: defer RCU sync for MNT_DETACH umount
Date: Fri, 26 Apr 2024 21:09:41 +0100 [thread overview]
Message-ID: <20240426200941.GP2118490@ZenIV> (raw)
In-Reply-To: <20240426195429.28547-2-lkarpins@redhat.com>
On Fri, Apr 26, 2024 at 03:53:48PM -0400, Lucas Karpinski wrote:
> -static void namespace_unlock(void)
> +static void free_mounts(struct hlist_head *mount_list)
> {
> - struct hlist_head head;
> struct hlist_node *p;
> struct mount *m;
> +
> + hlist_for_each_entry_safe(m, p, mount_list, mnt_umount) {
> + hlist_del(&m->mnt_umount);
> + mntput(&m->mnt);
... which may block in quite a few ways.
> + }
> +}
> +
> +static void delayed_mount_release(struct rcu_head *head)
> +{
> + struct mount_delayed_release *drelease =
> + container_of(head, struct mount_delayed_release, rcu);
> +
> + free_mounts(&drelease->release_list);
... and therefore so can this.
> + kfree(drelease);
> +}
> + call_rcu(&drelease->rcu, delayed_mount_release);
... which is a bad idea, since call_rcu() callbacks are run
from interrupt context. Which makes blocking in them a problem.
next prev parent reply other threads:[~2024-04-26 20:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-26 19:53 [RFC v2 0/1] fs/namespace: defer RCU sync for MNT_DETACH umount Lucas Karpinski
2024-04-26 19:53 ` [RFC v2 1/1] " Lucas Karpinski
2024-04-26 20:09 ` Al Viro [this message]
2024-04-30 13:25 ` Lucas Karpinski
2024-05-01 13:41 ` Ian Kent
2024-04-30 14:14 ` kernel test robot
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240426200941.GP2118490@ZenIV \
--to=viro@zeniv.linux.org.uk \
--cc=alexl@redhat.com \
--cc=brauner@kernel.org \
--cc=echanude@redhat.com \
--cc=ikent@redhat.com \
--cc=jack@suse.cz \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=lkarpins@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).