The patch titled
Subject: proc: use down_read_killable mmap_sem for /proc/pid/pagemap
has been added to the -mm tree. Its filename is
proc-use-down_read_killable-mmap_sem-for-proc-pid-pagemap.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-use-down_read_killable-mmap_sem-for-proc-pid-pagemap.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-use-down_read_killable-mmap_sem-for-proc-pid-pagemap.patch
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------------------------------------------------------
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Subject: proc: use down_read_killable mmap_sem for /proc/pid/pagemap
Do not remain stuck forever if something goes wrong. Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.
Link: http://lkml.kernel.org/r/156007493638.3335.4872164955523928492.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Reviewed-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Koutný <mkoutny@xxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/fs/proc/task_mmu.c~proc-use-down_read_killable-mmap_sem-for-proc-pid-pagemap
+++ a/fs/proc/task_mmu.c
@@ -1547,7 +1547,9 @@ static ssize_t pagemap_read(struct file
/* overflow ? */
if (end < start_vaddr || end > end_vaddr)
end = end_vaddr;
- down_read(&mm->mmap_sem);
+ ret = down_read_killable(&mm->mmap_sem);
+ if (ret)
+ goto out_free;
ret = walk_page_range(start_vaddr, end, &pagemap_walk);
up_read(&mm->mmap_sem);
start_vaddr = end;
_
Patches currently in -mm which might be from khlebnikov@xxxxxxxxxxxxxx are
proc-use-down_read_killable-mmap_sem-for-proc-pid-maps.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-smaps_rollup.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-pagemap.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-clear_refs.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-map_files.patch
mm-use-down_read_killable-for-locking-mmap_sem-in-access_remote_vm.patch
