From: Mikulas Patocka <mpatocka@redhat.com>
Date: Fri, 27 Mar 2020 11:22:36 +0000 (-0400)
Subject: dm writecache: add cond_resched to avoid CPU hangs
X-Git-Tag: v5.5.18~82
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b7ab21aa980aed6b820bde4962c42781b547ce7;p=thirdparty%2Fkernel%2Fstable.git

dm writecache: add cond_resched to avoid CPU hangs

commit 1edaa447d958bec24c6a79685a5790d98976fd16 upstream.

Initializing a dm-writecache device can take a long time when the
persistent memory device is large.  Add cond_resched() to a few loops
to avoid warnings that the CPU is stuck.

Cc: stable@vger.kernel.org # v4.18+
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/md/dm-writecache.c b/drivers/md/dm-writecache.c
index cd9e4c8a023a6..af190018d10a5 100644
--- a/drivers/md/dm-writecache.c
+++ b/drivers/md/dm-writecache.c
@@ -872,6 +872,7 @@ static int writecache_alloc_entries(struct dm_writecache *wc)
 		struct wc_entry *e = &wc->entries[b];
 		e->index = b;
 		e->write_in_progress = false;
+		cond_resched();
 	}
 
 	return 0;
@@ -926,6 +927,7 @@ static void writecache_resume(struct dm_target *ti)
 			e->original_sector = le64_to_cpu(wme.original_sector);
 			e->seq_count = le64_to_cpu(wme.seq_count);
 		}
+		cond_resched();
 	}
 #endif
 	for (b = 0; b < wc->n_blocks; b++) {
@@ -1770,8 +1772,10 @@ static int init_memory(struct dm_writecache *wc)
 	pmem_assign(sb(wc)->n_blocks, cpu_to_le64(wc->n_blocks));
 	pmem_assign(sb(wc)->seq_count, cpu_to_le64(0));
 
-	for (b = 0; b < wc->n_blocks; b++)
+	for (b = 0; b < wc->n_blocks; b++) {
 		write_original_sector_seq_count(wc, &wc->entries[b], -1, -1);
+		cond_resched();
+	}
 
 	writecache_flush_all_metadata(wc);
 	writecache_commit_flushed(wc, false);