[Devel] [PATCH RHEL7 COMMIT] ms/mm/memory-failure: share the i_mmap_rwsem

[Vasily Averin]

The commit is pushed to "branch-rh7-3.10.0-1160.6.1.vz7.171.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.6.1.vz7.171.1
------>
commit b23df19a9094951735485cff30ffed441d7f578a
Author: Davidlohr Bueso <dave at stgolabs.net>
Date:   Thu Dec 3 11:41:13 2020 +0300

    ms/mm/memory-failure: share the i_mmap_rwsem
    
    No brainer conversion: collect_procs_file() only schedules a process for
    later kill, share the lock, similarly to the anon vma variant.
    
    Signed-off-by: Davidlohr Bueso <dbueso at suse.de>
    Acked-by: "Kirill A. Shutemov" <kirill at shutemov.name>
    Acked-by: Hugh Dickins <hughd at google.com>
    Cc: Oleg Nesterov <oleg at redhat.com>
    Acked-by: Peter Zijlstra (Intel) <peterz at infradead.org>
    Cc: Rik van Riel <riel at redhat.com>
    Cc: Srikar Dronamraju <srikar at linux.vnet.ibm.com>
    Acked-by: Mel Gorman <mgorman at suse.de>
    Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    
    https://jira.sw.ru/browse/PSBM-122663
    (cherry picked from commit d28eb9c861f41aa2af4cfcc5eeeddff42b13d31e)
    Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
---
 mm/memory-failure.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index a0ea96c..808f91d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -496,7 +496,7 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill,
 	struct task_struct *tsk;
 	struct address_space *mapping = page->mapping;
 
-	i_mmap_lock_write(mapping);
+	i_mmap_lock_read(mapping);
 	qread_lock(&tasklist_lock);
 	for_each_process(tsk) {
 		pgoff_t pgoff = page_to_pgoff(page);
@@ -518,7 +518,7 @@ static void collect_procs_file(struct page *page, struct list_head *to_kill,
 		}
 	}
 	qread_unlock(&tasklist_lock);
-	i_mmap_unlock_write(mapping);
+	i_mmap_unlock_read(mapping);
 }
 
 /*