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authorKonstantin Khlebnikov <khlebnikov@yandex-team.ru>2019-07-12 06:59:50 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2019-07-12 21:05:46 +0300
commit8a713e7df3352b8d9392476e9cf29e4e185dac32 (patch)
tree9e9a73a224bf958b06ae277e285f35f68f9a3c08
parentcbf800d9c7fb38d953ba8ae1bd27a6382114c32e (diff)
downloadlinux-8a713e7df3352b8d9392476e9cf29e4e185dac32.tar.xz
proc: use down_read_killable mmap_sem for /proc/pid/maps
Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation. This function is also used for /proc/pid/smaps. Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Roman Gushchin <guro@fb.com> Reviewed-by: Cyrill Gorcunov <gorcunov@gmail.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/task_mmu.c6
-rw-r--r--fs/proc/task_nommu.c6
2 files changed, 10 insertions, 2 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 01d4eb0e6bd1..2bf210229daf 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -166,7 +166,11 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
if (!mm || !mmget_not_zero(mm))
return NULL;
- down_read(&mm->mmap_sem);
+ if (down_read_killable(&mm->mmap_sem)) {
+ mmput(mm);
+ return ERR_PTR(-EINTR);
+ }
+
hold_task_mempolicy(priv);
priv->tail_vma = get_gate_vma(mm);
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 36bf0f2e102e..7907e6419e57 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -211,7 +211,11 @@ static void *m_start(struct seq_file *m, loff_t *pos)
if (!mm || !mmget_not_zero(mm))
return NULL;
- down_read(&mm->mmap_sem);
+ if (down_read_killable(&mm->mmap_sem)) {
+ mmput(mm);
+ return ERR_PTR(-EINTR);
+ }
+
/* start from the Nth VMA */
for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
if (n-- == 0)