Commit a26a9781 authored Jul 11, 2019 by Konstantin Khlebnikov Committed by Linus Torvalds Jul 12, 2019

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 <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>

parent 8a713e7d

fs/proc/task_mmu.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -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;

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