proc: use down_read_killable mmap_sem for /proc/pid/smaps_rollup

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/156007493429.3335.14666825072272692455.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <[email protected]>
Reviewed-by: Roman Gushchin <[email protected]>
Reviewed-by: Cyrill Gorcunov <[email protected]>
Reviewed-by: Kirill Tkhai <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michal Koutný <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Konstantin Khlebnikov 2019-07-11 20:59:53 -07:00 • committed by Linus Torvalds
commit a26a978155

View file

@ -832,7 +832,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
memset(&mss, 0, sizeof(mss));
down_read(&mm->mmap_sem);
ret = down_read_killable(&mm->mmap_sem);
if (ret)
goto out_put_mm;
hold_task_mempolicy(priv);
for (vma = priv->mm->mmap; vma; vma = vma->vm_next) {
@ -849,8 +852,9 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
release_task_mempolicy(priv);
up_read(&mm->mmap_sem);
mmput(mm);
out_put_mm:
mmput(mm);
out_put_task:
put_task_struct(priv->task);
priv->task = NULL;