linux-kernel - [PATCH] fs/proc: Move kfree outside pde_unload

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 22 Aug 2012 11:38:29 -0500
From:	Nathan Zimmer <nzimmer@....com>
To:	unlisted-recipients:; (no To-header on input)
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	adobriyan@...il.com, Nathan Zimmer <nzimmer@....com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	David Woodhouse <dwmw2@...radead.org>
Subject: [PATCH] fs/proc: Move kfree outside pde_unload_lock

This moves a kfree outside a spinlock to help scaling on larger (512 core)
systems.

I ran a simple test which just reads from /proc/cpuinfo.
Lower is better, as you can see the worst case scenario is improved.

	baseline	moved kfree
tasks	read-sec	read-sec
1	0.0141		0.0141
2	0.0140		0.0140
4	0.0140		0.0141
8	0.0145		0.0145
16	0.0553		0.0548
32	0.1688		0.1622
64	0.5017		0.3856
128	1.7005		0.9710
256	5.2513		2.6519
512	8.0529		6.2976

Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: David Woodhouse <dwmw2@...radead.org>
Acked-by: Alexey Dobriyan <adobriyan@...il.com>
Signed-off-by: Nathan Zimmer <nzimmer@....com>
---
 fs/proc/inode.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 7ac817b..bf36266 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -403,9 +403,9 @@ static int proc_reg_release(struct inode *inode, struct file *file)
 	release = pde->proc_fops->release;
 	if (pdeo) {
 		list_del(&pdeo->lh);
-		kfree(pdeo);
 	}
 	spin_unlock(&pde->pde_unload_lock);
+	kfree(pdeo);
 
 	if (release)
 		rv = release(inode, file);
-- 
1.6.0.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/