+ mm-mlock-prepare-params-outside-critical-region.patch added to -mm tree

[akpm@xxxxxxxxxxxxxxxxxxxx]

Subject: + mm-mlock-prepare-params-outside-critical-region.patch added to -mm tree
To: davidlohr@xxxxxx,riel@xxxxxxxxxx,vbabka@xxxxxxx,walken@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 03 Dec 2013 14:58:02 -0800


The patch titled
     Subject: mm/mlock: prepare params outside critical region
has been added to the -mm tree.  Its filename is
     mm-mlock-prepare-params-outside-critical-region.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-mlock-prepare-params-outside-critical-region.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-mlock-prepare-params-outside-critical-region.patch

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------------------------------------------------------
From: Davidlohr Bueso <davidlohr@xxxxxx>
Subject: mm/mlock: prepare params outside critical region

All mlock related syscalls prepare lock limits, lengths and start
parameters with the mmap_sem held.  Move this logic outside of the
critical region.  For the case of mlock, continue incrementing the amount
already locked by mm->locked_vm with the rwsem taken.

Signed-off-by: Davidlohr Bueso <davidlohr@xxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Reviewed-by: Michel Lespinasse <walken@xxxxxxxxxx>
Acked-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/mlock.c |   18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff -puN mm/mlock.c~mm-mlock-prepare-params-outside-critical-region mm/mlock.c
--- a/mm/mlock.c~mm-mlock-prepare-params-outside-critical-region
+++ a/mm/mlock.c
@@ -689,19 +689,21 @@ SYSCALL_DEFINE2(mlock, unsigned long, st
 
 	lru_add_drain_all();	/* flush pagevec */
 
-	down_write(&current->mm->mmap_sem);
 	len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 	start &= PAGE_MASK;
 
-	locked = len >> PAGE_SHIFT;
-	locked += current->mm->locked_vm;
-
 	lock_limit = rlimit(RLIMIT_MEMLOCK);
 	lock_limit >>= PAGE_SHIFT;
+	locked = len >> PAGE_SHIFT;
+
+	down_write(&current->mm->mmap_sem);
+
+	locked += current->mm->locked_vm;
 
 	/* check against resource limits */
 	if ((locked <= lock_limit) || capable(CAP_IPC_LOCK))
 		error = do_mlock(start, len, 1);
+
 	up_write(&current->mm->mmap_sem);
 	if (!error)
 		error = __mm_populate(start, len, 0);
@@ -712,11 +714,13 @@ SYSCALL_DEFINE2(munlock, unsigned long,
 {
 	int ret;
 
-	down_write(&current->mm->mmap_sem);
 	len = PAGE_ALIGN(len + (start & ~PAGE_MASK));
 	start &= PAGE_MASK;
+
+	down_write(&current->mm->mmap_sem);
 	ret = do_mlock(start, len, 0);
 	up_write(&current->mm->mmap_sem);
+
 	return ret;
 }
 
@@ -761,12 +765,12 @@ SYSCALL_DEFINE1(mlockall, int, flags)
 	if (flags & MCL_CURRENT)
 		lru_add_drain_all();	/* flush pagevec */
 
-	down_write(&current->mm->mmap_sem);
-
 	lock_limit = rlimit(RLIMIT_MEMLOCK);
 	lock_limit >>= PAGE_SHIFT;
 
 	ret = -ENOMEM;
+	down_write(&current->mm->mmap_sem);
+
 	if (!(flags & MCL_CURRENT) || (current->mm->total_vm <= lock_limit) ||
 	    capable(CAP_IPC_LOCK))
 		ret = do_mlockall(flags);
_

Patches currently in -mm which might be from davidlohr@xxxxxx are

mm-mmapc-add-mlock_future_check-helper.patch
mm-mlock-prepare-params-outside-critical-region.patch
ipc-semc-avoid-overflow-of-semop-undo-semadj-value.patch
ipc-semc-avoid-overflow-of-semop-undo-semadj-value-fix.patch

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