+ pid-tighten-pidmap-spinlock-critical-section-by-removing-kfree.patch added to -mm tree

+ pid-tighten-pidmap-spinlock-critical-section-by-removing-kfree.patch added to -mm tree

[akpm]

The patch titled
     pid: tighten pidmap spinlock critical section by removing kfree()
has been added to the -mm tree.  Its filename is
     pid-tighten-pidmap-spinlock-critical-section-by-removing-kfree.patch

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out what to do about this

The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/

------------------------------------------------------
Subject: pid: tighten pidmap spinlock critical section by removing kfree()
From: André Goddard Rosa <andre.goddard@gmail.com>

Avoid calling kfree() under pidmap spinlock, calling it afterwards.

Normally kfree() is fast, but sometimes it can be slow, so avoid
calling it under the spinlock if we can do it.

Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/pid.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff -puN kernel/pid.c~pid-tighten-pidmap-spinlock-critical-section-by-removing-kfree kernel/pid.c
--- a/kernel/pid.c~pid-tighten-pidmap-spinlock-critical-section-by-removing-kfree
+++ a/kernel/pid.c
@@ -141,11 +141,12 @@ static int alloc_pidmap(struct pid_names
 			 * installing it:
 			 */
 			spin_lock_irq(&pidmap_lock);
-			if (map->page)
-				kfree(page);
-			else
+			if (!map->page) {
 				map->page = page;
+				page = NULL;
+			}
 			spin_unlock_irq(&pidmap_lock);
+			kfree(page);
 			if (unlikely(!map->page))
 				break;
 		}
_

Patches currently in -mm which might be from andre.goddard@gmail.com are

linux-next.patch
vsprintf-factorize-null-string.patch
vsprintf-pre-calculate-final-string-length-for-later-use.patch
vsprintf-give-it-some-care-to-please-checkpatchpl.patch
vsprintf-use-tolower-whenever-possible.patch
vsprintf-reduce-code-size-by-avoiding-extra-check.patch
vsprintf-move-local-vars-to-block-local-vars-and-remove-unneeded-ones.patch
vsprintf-factor-out-skip_space-code-in-a-separate-function.patch
vsprintf-reuse-almost-identical-simple_strtoulx-functions.patch
ctype-constify-read-only-_ctype-string.patch
string-factorize-skip_spaces-and-export-it-to-be-generally-available.patch
string-on-strstrip-first-remove-leading-spaces-before-running-over-str.patch
tree-wide-convert-open-calls-to-remove-spaces-to-skip_spaces-lib-function.patch
parser-remove-unnecessary-strlen.patch
pid-tighten-pidmap-spinlock-critical-section-by-removing-kfree.patch
pid-reduce-code-size-by-using-a-pointer-to-iterate-over-array.patch

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