From: Konstantin Khlebnikov <khlebni...@yandex-team.ru> [ Upstream commit ad80b932c57d85fd6377f97f359b025baf179a87 ]
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 <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 | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 4d9a8e72d91f..1d9c63cd8a3c 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1543,7 +1543,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, /* 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; -- 2.20.1
