diff options
| author | Johannes Weiner <hannes@cmpxchg.org> | 2016-02-02 16:57:29 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-08 11:49:48 +0200 |
| commit | 57b796481cd8fa9883ba3fa1114b74e5736c6afd (patch) | |
| tree | ba3a108243a6f6d2de5e666846b64e0d417cb497 /include | |
| parent | fe0111391b214eeffdf6b380341ab0a1b97e6279 (diff) | |
proc: revert /proc/<pid>/maps [stack:TID] annotation
commit 65376df582174ffcec9e6471bf5b0dd79ba05e4a upstream.
Commit b76437579d13 ("procfs: mark thread stack correctly in
proc/<pid>/maps") added [stack:TID] annotation to /proc/<pid>/maps.
Finding the task of a stack VMA requires walking the entire thread list,
turning this into quadratic behavior: a thousand threads means a
thousand stacks, so the rendering of /proc/<pid>/maps needs to look at a
million combinations.
The cost is not in proportion to the usefulness as described in the
patch.
Drop the [stack:TID] annotation to make /proc/<pid>/maps (and
/proc/<pid>/numa_maps) usable again for higher thread counts.
The [stack] annotation inside /proc/<pid>/task/<tid>/maps is retained, as
identifying the stack VMA there is an O(1) operation.
Siddesh said:
"The end users needed a way to identify thread stacks programmatically and
there wasn't a way to do that. I'm afraid I no longer remember (or have
access to the resources that would aid my memory since I changed
employers) the details of their requirement. However, I did do this on my
own time because I thought it was an interesting project for me and nobody
really gave any feedback then as to its utility, so as far as I am
concerned you could roll back the main thread maps information since the
information is available in the thread-specific files"
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Siddhesh Poyarekar <siddhesh.poyarekar@gmail.com>
Cc: Shaohua Li <shli@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mm.h | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 54ad2e45bc6b..5adffb0a468f 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1242,8 +1242,7 @@ int set_page_dirty_lock(struct page *page); int clear_page_dirty_for_io(struct page *page); int get_cmdline(struct task_struct *task, char *buffer, int buflen); -extern struct task_struct *task_of_stack(struct task_struct *task, - struct vm_area_struct *vma, bool in_group); +int vma_is_stack_for_task(struct vm_area_struct *vma, struct task_struct *t); extern unsigned long move_page_tables(struct vm_area_struct *vma, unsigned long old_addr, struct vm_area_struct *new_vma, |