The patch titled
Subject: mm, util: account_locked_vm() does not hold mmap_lock
has been added to the -mm tree. Its filename is
mm-util-account_locked_vm-does-not-hold-mmap_lock.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-util-account_locked_vm-does-not-hold-mmap_lock.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-util-account_locked_vm-does-not-hold-mmap_lock.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Pengfei Li <fly@xxxxxxxxxxx>
Subject: mm, util: account_locked_vm() does not hold mmap_lock
Since mm->locked_vm is already an atomic counter, account_locked_vm()
does not need to hold mmap_lock.
Link: http://lkml.kernel.org/r/20200726080224.205470-2-fly@xxxxxxxxxxx
Signed-off-by: Pengfei Li <fly@xxxxxxxxxxx>
Cc: Bernard Metzler <bmt@xxxxxxxxxxxxxx>
Cc: Doug Ledford <dledford@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: "Kirill A . Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
Cc: Michel Lespinasse <walken@xxxxxxxxxx>
Cc: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Cc: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dbueso@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Liam Howlett <Liam.Howlett@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 8 ++------
mm/util.c | 15 +++------------
2 files changed, 5 insertions(+), 18 deletions(-)
--- a/drivers/vfio/vfio_iommu_type1.c~mm-util-account_locked_vm-does-not-hold-mmap_lock
+++ a/drivers/vfio/vfio_iommu_type1.c
@@ -376,12 +376,8 @@ static int vfio_lock_acct(struct vfio_dm
if (!mm)
return -ESRCH; /* process exited */
- ret = mmap_write_lock_killable(mm);
- if (!ret) {
- ret = __account_locked_vm(mm, abs(npage), npage > 0, dma->task,
- dma->lock_cap);
- mmap_write_unlock(mm);
- }
+ ret = __account_locked_vm(mm, abs(npage), npage > 0,
+ dma->task, dma->lock_cap);
if (async)
mmput(mm);
--- a/mm/util.c~mm-util-account_locked_vm-does-not-hold-mmap_lock
+++ a/mm/util.c
@@ -424,8 +424,7 @@ void arch_pick_mmap_layout(struct mm_str
* @task: task used to check RLIMIT_MEMLOCK
* @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
*
- * Assumes @task and @mm are valid (i.e. at least one reference on each), and
- * that mmap_lock is held as writer.
+ * Assumes @task and @mm are valid (i.e. at least one reference on each).
*
* Return:
* * 0 on success
@@ -437,8 +436,6 @@ int __account_locked_vm(struct mm_struct
unsigned long locked_vm, limit;
int ret = 0;
- mmap_assert_write_locked(mm);
-
locked_vm = atomic64_read(&mm->locked_vm);
if (inc) {
if (!bypass_rlim) {
@@ -476,17 +473,11 @@ EXPORT_SYMBOL_GPL(__account_locked_vm);
*/
int account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc)
{
- int ret;
-
if (pages == 0 || !mm)
return 0;
- mmap_write_lock(mm);
- ret = __account_locked_vm(mm, pages, inc, current,
- capable(CAP_IPC_LOCK));
- mmap_write_unlock(mm);
-
- return ret;
+ return __account_locked_vm(mm, pages, inc,
+ current, capable(CAP_IPC_LOCK));
}
EXPORT_SYMBOL_GPL(account_locked_vm);
_
Patches currently in -mm which might be from fly@xxxxxxxxxxx are
mm-make-mm-locked_vm-an-atomic64-counter.patch
mm-util-account_locked_vm-does-not-hold-mmap_lock.patch
