From: Oscar Salvador <osalvador@suse.de>
To: Laurent Cremmer <laurent@oss.volkswagen.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mina Almasry <almasrymina@google.com>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH] hugetlb: fix locking in region_add,region_cgh,allocate_file_region_entries
Date: Fri, 23 Oct 2020 13:02:08 +0200 [thread overview]
Message-ID: <20201023110204.GA3925@linux> (raw)
In-Reply-To: <20201023074759.46605-1-laurent@oss.volkswagen.com>
On Fri, Oct 23, 2020 at 09:47:59AM +0200, Laurent Cremmer wrote:
> The third instance spotted by manual examination.
It is friday, I might be overlooking something obvious, so bear with me.
> In static long region_add(...) and static long region_cgh(...) , releasing
> the acquired lock when exiting via their error path was removed.
> This will cause these functions to return with a lock held if they do not
> succeed.
If they do not suceed, it means that allocate_file_region_entries returned
non-zero, which means that we hit:
spin_unlock(&resv->lock);
for (i = 0; i < to_allocate; i++) {
trg = kmalloc(sizeof(*trg), GFP_KERNEL);
if (!trg)
goto out_of_memory;
list_add(&trg->link, &allocated_regions);
}
So, we do spin_unlock before jumping to out_of_memory.
> A a new function allocate_file_region_entries was also introduced that
> must be called with a lock held and returned with the lock held.
> However the lock is temporarily released during processing but will not
> be reacquired on error.
As stated above, region_add/region_chr exit immediately on allocate_file_region_entries
failure, so it does not need to acquire the lock.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2020-10-23 11:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-23 7:47 Laurent Cremmer
2020-10-23 10:12 ` David Hildenbrand
2020-10-23 11:25 ` Laurent Cremmer
2020-10-23 11:39 ` David Hildenbrand
2020-10-23 11:02 ` Oscar Salvador [this message]
2020-10-23 11:32 ` Laurent Cremmer
2020-10-23 12:11 ` Oscar Salvador
2020-10-23 16:47 ` Mike Kravetz
2020-10-27 7:34 ` Laurent Cremmer
2020-10-28 19:18 ` Mina Almasry
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=20201023110204.GA3925@linux \
--to=osalvador@suse.de \
--cc=akpm@linux-foundation.org \
--cc=almasrymina@google.com \
--cc=laurent@oss.volkswagen.com \
--cc=linux-mm@kvack.org \
--cc=mike.kravetz@oracle.com \
--cc=rientjes@google.com \
--cc=skhan@linuxfoundation.org \
/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