Patch "jffs2: avoid soft-lockup in jffs2_reserve_space_gc()" has been added to the 3.4-stable tree

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This is a note to let you know that I've just added the patch titled

    jffs2: avoid soft-lockup in jffs2_reserve_space_gc()

to the 3.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     jffs2-avoid-soft-lockup-in-jffs2_reserve_space_gc.patch
and it can be found in the queue-3.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From 13b546d96207c131eeae15dc7b26c6e7d0f1cad7 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizefan@xxxxxxxxxx>
Date: Wed, 12 Feb 2014 12:44:56 -0800
Subject: jffs2: avoid soft-lockup in jffs2_reserve_space_gc()

From: Li Zefan <lizefan@xxxxxxxxxx>

commit 13b546d96207c131eeae15dc7b26c6e7d0f1cad7 upstream.

We triggered soft-lockup under stress test on 2.6.34 kernel.

BUG: soft lockup - CPU#1 stuck for 60009ms! [lockf2.test:14488]
...
[<bf09a4d4>] (jffs2_do_reserve_space+0x420/0x440 [jffs2])
[<bf09a528>] (jffs2_reserve_space_gc+0x34/0x78 [jffs2])
[<bf0a1350>] (jffs2_garbage_collect_dnode.isra.3+0x264/0x478 [jffs2])
[<bf0a2078>] (jffs2_garbage_collect_pass+0x9c0/0xe4c [jffs2])
[<bf09a670>] (jffs2_reserve_space+0x104/0x2a8 [jffs2])
[<bf09dc48>] (jffs2_write_inode_range+0x5c/0x4d4 [jffs2])
[<bf097d8c>] (jffs2_write_end+0x198/0x2c0 [jffs2])
[<c00e00a4>] (generic_file_buffered_write+0x158/0x200)
[<c00e14f4>] (__generic_file_aio_write+0x3a4/0x414)
[<c00e15c0>] (generic_file_aio_write+0x5c/0xbc)
[<c012334c>] (do_sync_write+0x98/0xd4)
[<c0123a84>] (vfs_write+0xa8/0x150)
[<c0123d74>] (sys_write+0x3c/0xc0)]

Fix this by adding a cond_resched() in the while loop.

[akpm@xxxxxxxxxxxxxxxxxxxx: don't initialize `ret']
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx>
Cc: Artem Bityutskiy <artem.bityutskiy@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Brian Norris <computersforpeace@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 fs/jffs2/nodemgmt.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

--- a/fs/jffs2/nodemgmt.c
+++ b/fs/jffs2/nodemgmt.c
@@ -169,20 +169,25 @@ int jffs2_reserve_space(struct jffs2_sb_
 int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize,
 			   uint32_t *len, uint32_t sumsize)
 {
-	int ret = -EAGAIN;
+	int ret;
 	minsize = PAD(minsize);
 
 	jffs2_dbg(1, "%s(): Requested 0x%x bytes\n", __func__, minsize);
 
-	spin_lock(&c->erase_completion_lock);
-	while(ret == -EAGAIN) {
+	while (true) {
+		spin_lock(&c->erase_completion_lock);
 		ret = jffs2_do_reserve_space(c, minsize, len, sumsize);
 		if (ret) {
 			jffs2_dbg(1, "%s(): looping, ret is %d\n",
 				  __func__, ret);
 		}
+		spin_unlock(&c->erase_completion_lock);
+
+		if (ret == -EAGAIN)
+			cond_resched();
+		else
+			break;
 	}
-	spin_unlock(&c->erase_completion_lock);
 	if (!ret)
 		ret = jffs2_prealloc_raw_node_refs(c, c->nextblock, 1);
 


Patches currently in stable-queue which might be from lizefan@xxxxxxxxxx are

queue-3.4/jffs2-avoid-soft-lockup-in-jffs2_reserve_space_gc.patch
queue-3.4/jffs2-remove-from-wait-queue-after-schedule.patch
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