From: Al Viro <viro@zeniv.linux.org.uk>
To: Gautham Ananthakrishna <gautham.ananthakrishna@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, matthew.wilcox@oracle.com,
khlebnikov@yandex-team.ru
Subject: Re: [PATCH RFC 6/6] dcache: prevent flooding with negative dentries
Date: Wed, 14 Apr 2021 03:56:44 +0000 [thread overview]
Message-ID: <YHZn/IFvZbMX9QTD@zeniv-ca.linux.org.uk> (raw)
In-Reply-To: <1611235185-1685-7-git-send-email-gautham.ananthakrishna@oracle.com>
On Thu, Jan 21, 2021 at 06:49:45PM +0530, Gautham Ananthakrishna wrote:
> + spin_lock(&victim->d_lock);
> + parent = lock_parent(victim);
> +
> + rcu_read_unlock();
Similar story. As soon as you hit that rcu_read_unlock(), the memory
pointed to by victim might be reused. If you have hit __lock_parent(),
victim->d_lock had been dropped and regained. Which means that freeing
might've been already scheduled. Unlike #1/6, here you won't get
memory corruption in lock_parent() itself, but...
> +
> + if (d_count(victim) || !d_is_negative(victim) ||
> + (victim->d_flags & DCACHE_REFERENCED)) {
> + if (parent)
> + spin_unlock(&parent->d_lock);
> + spin_unlock(&victim->d_lock);
... starting from here you just might.
next prev parent reply other threads:[~2021-04-14 3:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-21 13:19 [PATCH RFC 0/6] fix the negative dentres bloating system memory usage Gautham Ananthakrishna
2021-01-21 13:19 ` [PATCH RFC 1/6] dcache: sweep cached negative dentries to the end of list of siblings Gautham Ananthakrishna
2021-04-14 3:00 ` Al Viro
2021-04-15 16:50 ` Al Viro
2021-04-14 3:41 ` Al Viro
2021-04-15 16:25 ` Al Viro
2021-01-21 13:19 ` [PATCH RFC 2/6] fsnotify: stop walking child dentries if remaining tail is negative Gautham Ananthakrishna
2021-01-21 13:19 ` [PATCH RFC 3/6] dcache: add action D_WALK_SKIP_SIBLINGS to d_walk() Gautham Ananthakrishna
2021-01-21 13:19 ` [PATCH RFC 4/6] dcache: stop walking siblings if remaining dentries all negative Gautham Ananthakrishna
2021-01-21 13:19 ` [PATCH RFC 5/6] dcache: push releasing dentry lock into sweep_negative Gautham Ananthakrishna
2021-01-21 13:19 ` [PATCH RFC 6/6] dcache: prevent flooding with negative dentries Gautham Ananthakrishna
2021-04-14 3:56 ` Al Viro [this message]
2021-03-31 14:23 ` [PATCH RFC 0/6] fix the negative dentres bloating system memory usage Matthew Wilcox
2021-04-14 2:40 ` Al Viro
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=YHZn/IFvZbMX9QTD@zeniv-ca.linux.org.uk \
--to=viro@zeniv.linux.org.uk \
--cc=gautham.ananthakrishna@oracle.com \
--cc=khlebnikov@yandex-team.ru \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=matthew.wilcox@oracle.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 NNTP newsgroup(s).