linux-kernel - [PATCH] memcg: fix shmem_unuse

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 for Android: free password hash cracker in your pocket

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

Message-ID: <Pine.LNX.4.64.0806290108110.20280@blonde.site>
Date:	Sun, 29 Jun 2008 01:13:20 +0100 (BST)
From:	Hugh Dickins <hugh@...itas.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
cc:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Balbir Singh <balbir@...ibm.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] memcg: fix shmem_unuse_inode charging

The mem_cgroup_cache_charge in shmem_unuse_inode has been moved after
the radix_tree_preload, so generating a BUG: sleeping function called
from invalid context.  Move it back, uncharging where necessary.

Signed-off-by: Hugh Dickins <hugh@...itas.com>
---
Should follow mmotm's memcg-remove-refcnt-from-page_cgroup.patch

mm/shmem.c |   28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

--- mmotm/mm/shmem.c	2008-06-27 13:39:20.000000000 +0100
+++ linux/mm/shmem.c	2008-06-27 17:25:41.000000000 +0100
@@ -922,27 +922,24 @@ found:
 	error = 1;
 	if (!inode)
 		goto out;
-	error = radix_tree_preload(GFP_KERNEL);
-	if (error)
-		goto out;
-	/*
-	 * Because we use GFP_NOWAIT in add_to_page_cache(), we can see -ENOMEM
-	 * failure because of memory pressure in memory resource controller.
-	 * Then, precharge page while we can wait, uncharge at failure will be
-	 * automatically done in add_to_page_cache()
-	 */
+	/* Precharge page using GFP_KERNEL while we can wait */
 	error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
 	if (error)
-		goto preload_out;
-
+		goto out;
+	error = radix_tree_preload(GFP_KERNEL);
+	if (error) {
+		mem_cgroup_uncharge_cache_page(page);
+		goto out;
+	}
 	error = 1;
 
 	spin_lock(&info->lock);
 	ptr = shmem_swp_entry(info, idx, NULL);
-	if (ptr && ptr->val == entry.val)
-		error = add_to_page_cache(page, inode->i_mapping, idx,
-					GFP_NOWAIT);
-	else /* we don't have to account this page. */
+	if (ptr && ptr->val == entry.val) {
+		error = add_to_page_cache(page, inode->i_mapping,
+						idx, GFP_NOWAIT);
+		/* does mem_cgroup_uncharge_cache_page on error */
+	} else	/* we must compensate for our precharge above */
 		mem_cgroup_uncharge_cache_page(page);
 
 	if (error == -EEXIST) {
@@ -969,7 +966,6 @@ found:
 	if (ptr)
 		shmem_swp_unmap(ptr);
 	spin_unlock(&info->lock);
-preload_out:
 	radix_tree_preload_end();
 out:
 	unlock_page(page);
--
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/