Patch "staging/lustre/osc: Revert erroneous list_for_each_entry_safe use" has been added to the 4.9-stable tree

Patch "staging/lustre/osc: Revert erroneous list_for_each_entry_safe use" has been added to the 4.9-stable tree

[gregkh]

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

    staging/lustre/osc: Revert erroneous list_for_each_entry_safe use

to the 4.9-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:
     staging-lustre-osc-revert-erroneous-list_for_each_entry_safe-use.patch
and it can be found in the queue-4.9 subdirectory.

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


>From cd15dd6ef4ea11df87f717b8b1b83aaa738ec8af Mon Sep 17 00:00:00 2001
From: Oleg Drokin <green@linuxhacker.ru>
Date: Tue, 6 Dec 2016 22:53:48 -0500
Subject: staging/lustre/osc: Revert erroneous list_for_each_entry_safe use

From: Oleg Drokin <green@linuxhacker.ru>

commit cd15dd6ef4ea11df87f717b8b1b83aaa738ec8af upstream.

I have been having a lot of unexplainable crashes in osc_lru_shrink
lately that I could not see a good explanation for and then I found
this patch that slip under the radar somehow that incorrectly
converted while loop for lru list iteration into
list_for_each_entry_safe totally ignoring that in the body of
the loop we drop spinlocks guarding this list and move list entries
around.
Not sure why it was not showing up right away, perhaps some of the
more recent LRU changes committed caused some extra pressure on this
code that finally highlighted the breakage.

Reverts: 8adddc36b1fc ("staging: lustre: osc: Use list_for_each_entry_safe")
CC: Bhaktipriya Shridhar <bhaktipriya96@gmail.com>
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/staging/lustre/lustre/osc/osc_page.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/staging/lustre/lustre/osc/osc_page.c
+++ b/drivers/staging/lustre/lustre/osc/osc_page.c
@@ -542,7 +542,6 @@ long osc_lru_shrink(const struct lu_env
 	struct cl_object *clobj = NULL;
 	struct cl_page **pvec;
 	struct osc_page *opg;
-	struct osc_page *temp;
 	int maxscan = 0;
 	long count = 0;
 	int index = 0;
@@ -569,13 +568,15 @@ long osc_lru_shrink(const struct lu_env
 
 	spin_lock(&cli->cl_lru_list_lock);
 	maxscan = min(target << 1, atomic_long_read(&cli->cl_lru_in_list));
-	list_for_each_entry_safe(opg, temp, &cli->cl_lru_list, ops_lru) {
+	while (!list_empty(&cli->cl_lru_list)) {
 		struct cl_page *page;
 		bool will_free = false;
 
 		if (--maxscan < 0)
 			break;
 
+		opg = list_entry(cli->cl_lru_list.next, struct osc_page,
+				 ops_lru);
 		page = opg->ops_cl.cpl_page;
 		if (lru_page_busy(cli, page)) {
 			list_move_tail(&opg->ops_lru, &cli->cl_lru_list);


Patches currently in stable-queue which might be from green@linuxhacker.ru are

queue-4.9/staging-lustre-osc-revert-erroneous-list_for_each_entry_safe-use.patch