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>alistair/sunxi64-5.4-dsi
parent
8a713e7df3
commit
a26a978155
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@ -832,7 +832,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
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memset(&mss, 0, sizeof(mss));
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memset(&mss, 0, sizeof(mss));
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down_read(&mm->mmap_sem);
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ret = down_read_killable(&mm->mmap_sem);
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if (ret)
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goto out_put_mm;
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hold_task_mempolicy(priv);
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hold_task_mempolicy(priv);
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for (vma = priv->mm->mmap; vma; vma = vma->vm_next) {
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for (vma = priv->mm->mmap; vma; vma = vma->vm_next) {
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@ -849,8 +852,9 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
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release_task_mempolicy(priv);
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release_task_mempolicy(priv);
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up_read(&mm->mmap_sem);
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up_read(&mm->mmap_sem);
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mmput(mm);
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out_put_mm:
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mmput(mm);
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out_put_task:
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out_put_task:
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put_task_struct(priv->task);
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put_task_struct(priv->task);
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priv->task = NULL;
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priv->task = NULL;
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