Do not stuck forever if something wrong. Killable lock allows to cleanup stuck tasks and simplifies investigation.
Replace the only unkillable mmap_sem lock in clear_refs_write. 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]> --- fs/proc/task_mmu.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 78bed6adc62d..7f84d1477b5b 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1140,7 +1140,10 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf, goto out_mm; } - down_read(&mm->mmap_sem); + if (down_read_killable(&mm->mmap_sem)) { + count = -EINTR; + goto out_mm; + } tlb_gather_mmu(&tlb, mm, 0, -1); if (type == CLEAR_REFS_SOFT_DIRTY) { for (vma = mm->mmap; vma; vma = vma->vm_next) {
