From: Konstantin Khlebnikov <khlebni...@yandex-team.ru> [ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ]
Do not remain stuck forever if something goes wrong. Using a killable lock permits cleanup of stuck tasks and simplifies investigation. Replace the only unkillable mmap_sem lock in clear_refs_write(). Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebni...@yandex-team.ru> Reviewed-by: Roman Gushchin <g...@fb.com> Reviewed-by: Cyrill Gorcunov <gorcu...@gmail.com> Reviewed-by: Kirill Tkhai <ktk...@virtuozzo.com> Acked-by: Michal Hocko <mho...@suse.com> Cc: Alexey Dobriyan <adobri...@gmail.com> Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: Matthew Wilcox <wi...@infradead.org> Cc: Michal Koutný <mkou...@suse.com> Cc: Oleg Nesterov <o...@redhat.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Sasha Levin <sas...@kernel.org> --- 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 8b1376c42647..d544ab2e4210 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1136,7 +1136,10 @@ 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) { -- 2.20.1
