3.0-stable patches

added patches:
	fix-shrink_dcache_parent-livelock.patch

diff --git a/queue-3.0/fix-shrink_dcache_parent-livelock.patch b/queue-3.0/fix-shrink_dcache_parent-livelock.patch
new file mode 100644 (file)
index 0000000..9d988db
--- /dev/null
+++ b/queue-3.0/fix-shrink_dcache_parent-livelock.patch
@@ -0,0 +1,125 @@
+From eaf5f9073533cde21c7121c136f1c3f072d9cf59 Mon Sep 17 00:00:00 2001
+From: Miklos Szeredi <miklos@szeredi.hu>
+Date: Tue, 10 Jan 2012 18:22:25 +0100
+Subject: fix shrink_dcache_parent() livelock
+
+From: Miklos Szeredi <miklos@szeredi.hu>
+
+commit eaf5f9073533cde21c7121c136f1c3f072d9cf59 upstream.
+
+Two (or more) concurrent calls of shrink_dcache_parent() on the same dentry may
+cause shrink_dcache_parent() to loop forever.
+
+Here's what appears to happen:
+
+1 - CPU0: select_parent(P) finds C and puts it on dispose list, returns 1
+
+2 - CPU1: select_parent(P) locks P->d_lock
+
+3 - CPU0: shrink_dentry_list() locks C->d_lock
+   dentry_kill(C) tries to lock P->d_lock but fails, unlocks C->d_lock
+
+4 - CPU1: select_parent(P) locks C->d_lock,
+         moves C from dispose list being processed on CPU0 to the new
+dispose list, returns 1
+
+5 - CPU0: shrink_dentry_list() finds dispose list empty, returns
+
+6 - Goto 2 with CPU0 and CPU1 switched
+
+Basically select_parent() steals the dentry from shrink_dentry_list() and thinks
+it found a new one, causing shrink_dentry_list() to think it's making progress
+and loop over and over.
+
+One way to trigger this is to make udev calls stat() on the sysfs file while it
+is going away.
+
+Having a file in /lib/udev/rules.d/ with only this one rule seems to the trick:
+
+ATTR{vendor}=="0x8086", ATTR{device}=="0x10ca", ENV{PCI_SLOT_NAME}="%k", ENV{MATCHADDR}="$attr{address}", RUN+="/bin/true"
+
+Then execute the following loop:
+
+while true; do
+        echo -bond0 > /sys/class/net/bonding_masters
+        echo +bond0 > /sys/class/net/bonding_masters
+        echo -bond1 > /sys/class/net/bonding_masters
+        echo +bond1 > /sys/class/net/bonding_masters
+done
+
+One fix would be to check all callers and prevent concurrent calls to
+shrink_dcache_parent().  But I think a better solution is to stop the
+stealing behavior.
+
+This patch adds a new dentry flag that is set when the dentry is added to the
+dispose list.  The flag is cleared in dentry_lru_del() in case the dentry gets a
+new reference just before being pruned.
+
+If the dentry has this flag, select_parent() will skip it and let
+shrink_dentry_list() retry pruning it.  With select_parent() skipping those
+dentries there will not be the appearance of progress (new dentries found) when
+there is none, hence shrink_dcache_parent() will not loop forever.
+
+Set the flag is also set in prune_dcache_sb() for consistency as suggested by
+Linus.
+
+Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
+Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
+
+---
+ fs/dcache.c            |   14 ++++++++++----
+ include/linux/dcache.h |    1 +
+ 2 files changed, 11 insertions(+), 4 deletions(-)
+
+--- a/fs/dcache.c
++++ b/fs/dcache.c
+@@ -241,6 +241,7 @@ static void dentry_lru_add(struct dentry
+ static void __dentry_lru_del(struct dentry *dentry)
+ {
+       list_del_init(&dentry->d_lru);
++      dentry->d_flags &= ~DCACHE_SHRINK_LIST;
+       dentry->d_sb->s_nr_dentry_unused--;
+       dentry_stat.nr_unused--;
+ }
+@@ -753,6 +754,7 @@ relock:
+                       spin_unlock(&dentry->d_lock);
+               } else {
+                       list_move_tail(&dentry->d_lru, &tmp);
++                      dentry->d_flags |= DCACHE_SHRINK_LIST;
+                       spin_unlock(&dentry->d_lock);
+                       if (!--cnt)
+                               break;
+@@ -1144,14 +1146,18 @@ resume:
+               /* 
+                * move only zero ref count dentries to the end 
+                * of the unused list for prune_dcache
++               *
++               * Those which are presently on the shrink list, being processed
++               * by shrink_dentry_list(), shouldn't be moved.  Otherwise the
++               * loop in shrink_dcache_parent() might not make any progress
++               * and loop forever.
+                */
+-              if (!dentry->d_count) {
++              if (dentry->d_count) {
++                      dentry_lru_del(dentry);
++              } else if (!(dentry->d_flags & DCACHE_SHRINK_LIST)) {
+                       dentry_lru_move_tail(dentry);
+                       found++;
+-              } else {
+-                      dentry_lru_del(dentry);
+               }
+-
+               /*
+                * We can return to the caller if we have found some (this
+                * ensures forward progress). We'll be coming back to find
+--- a/include/linux/dcache.h
++++ b/include/linux/dcache.h
+@@ -207,6 +207,7 @@ struct dentry_operations {
+ 
+ #define DCACHE_CANT_MOUNT     0x0100
+ #define DCACHE_GENOCIDE               0x0200
++#define DCACHE_SHRINK_LIST    0x0400
+ 
+ #define DCACHE_OP_HASH                0x1000
+ #define DCACHE_OP_COMPARE     0x2000

diff --git a/queue-3.0/series b/queue-3.0/series
index 7d6def1c35475e7d00551c9a4fc6b9bc499de158..2d65bfa10317cc228689a82af1e2365f125a81ce 100644 (file)
--- a/queue-3.0/series
+++ b/queue-3.0/series
@@ -50,3 +50,4 @@ fsnotify-don-t-bug-in-fsnotify_destroy_mark.patch
 x86-uv-update-boot-messages-for-sgi-uv2-platform.patch
 recordmcount-fix-handling-of-elf64-big-endian-objects.patch
 uvcvideo-fix-integer-overflow-in-uvc_ioctl_ctrl_map.patch
+fix-shrink_dcache_parent-livelock.patch