From: Daniel Jordan <daniel.m.jordan@oracle.com>
To: linux-mm@kvack.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: aarcange@redhat.com, aaron.lu@intel.com,
akpm@linux-foundation.org, alex.williamson@redhat.com,
bsd@redhat.com, daniel.m.jordan@oracle.com,
darrick.wong@oracle.com, dave.hansen@linux.intel.com,
jgg@mellanox.com, jwadams@google.com, jiangshanlai@gmail.com,
mhocko@kernel.org, mike.kravetz@oracle.com,
Pavel.Tatashin@microsoft.com, prasad.singamsetty@oracle.com,
rdunlap@infradead.org, steven.sistare@oracle.com,
tim.c.chen@intel.com, tj@kernel.org, vbabka@suse.cz
Subject: [RFC PATCH v4 08/13] vfio: remove unnecessary mmap_sem writer acquisition around locked_vm
Date: Mon, 5 Nov 2018 11:55:53 -0500 [thread overview]
Message-ID: <20181105165558.11698-9-daniel.m.jordan@oracle.com> (raw)
In-Reply-To: <20181105165558.11698-1-daniel.m.jordan@oracle.com>
Now that mmap_sem is no longer required for modifying locked_vm, remove
it in the VFIO code.
[XXX Can be sent separately, along with similar conversions in the other
places mmap_sem was taken for locked_vm. While at it, could make
similar changes to pinned_vm.]
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
---
drivers/vfio/vfio_iommu_type1.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index f307dc9d5e19..9e52a24eb45b 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -258,7 +258,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
{
struct mm_struct *mm;
- int ret;
+ long locked_vm;
+ int ret = 0;
if (!npage)
return 0;
@@ -267,24 +268,15 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
if (!mm)
return -ESRCH; /* process exited */
- ret = down_write_killable(&mm->mmap_sem);
- if (!ret) {
- if (npage > 0) {
- if (!dma->lock_cap) {
- unsigned long limit;
-
- limit = task_rlimit(dma->task,
- RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+ locked_vm = atomic_long_add_return(npage, &mm->locked_vm);
- if (atomic_long_read(&mm->locked_vm) + npage > limit)
- ret = -ENOMEM;
- }
+ if (npage > 0 && !dma->lock_cap) {
+ unsigned long limit = task_rlimit(dma->task, RLIMIT_MEMLOCK) >>
+ PAGE_SHIFT;
+ if (locked_vm > limit) {
+ atomic_long_sub(npage, &mm->locked_vm);
+ ret = -ENOMEM;
}
-
- if (!ret)
- atomic_long_add(npage, &mm->locked_vm);
-
- up_write(&mm->mmap_sem);
}
if (async)
--
2.19.1
next prev parent reply other threads:[~2018-11-05 16:59 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-05 16:55 [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 01/13] ktask: add documentation Daniel Jordan
2018-11-05 21:19 ` Randy Dunlap
2018-11-06 2:27 ` Daniel Jordan
2018-11-06 8:49 ` Peter Zijlstra
2018-11-06 20:34 ` Daniel Jordan
2018-11-06 20:51 ` Jason Gunthorpe
2018-11-07 10:27 ` Peter Zijlstra
2018-11-07 20:21 ` Daniel Jordan
2018-11-07 10:35 ` Peter Zijlstra
2018-11-07 21:20 ` Daniel Jordan
2018-11-08 17:26 ` Jonathan Corbet
2018-11-08 19:15 ` Daniel Jordan
2018-11-08 19:24 ` Jonathan Corbet
2018-11-27 19:50 ` Pavel Machek
2018-11-28 16:56 ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 02/13] ktask: multithread CPU-intensive kernel work Daniel Jordan
2018-11-05 20:51 ` Randy Dunlap
2018-11-06 2:24 ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 03/13] ktask: add undo support Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 04/13] ktask: run helper threads at MAX_NICE Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 05/13] workqueue, ktask: renice helper threads to prevent starvation Daniel Jordan
2018-11-13 16:34 ` Tejun Heo
2018-11-19 16:45 ` Daniel Jordan
2018-11-20 16:33 ` Tejun Heo
2018-11-20 17:03 ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 06/13] vfio: parallelize vfio_pin_map_dma Daniel Jordan
2018-11-05 21:51 ` Alex Williamson
2018-11-06 2:42 ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 07/13] mm: change locked_vm's type from unsigned long to atomic_long_t Daniel Jordan
2018-11-05 16:55 ` Daniel Jordan [this message]
2018-11-05 16:55 ` [RFC PATCH v4 09/13] vfio: relieve mmap_sem reader cacheline bouncing by holding it longer Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 10/13] mm: enlarge type of offset argument in mem_map_offset and mem_map_next Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 11/13] mm: parallelize deferred struct page initialization within each node Daniel Jordan
2018-11-10 3:48 ` Elliott, Robert (Persistent Memory)
2018-11-12 16:54 ` Daniel Jordan
2018-11-12 22:15 ` Elliott, Robert (Persistent Memory)
2018-11-19 16:01 ` Daniel Jordan
2018-11-27 0:12 ` Elliott, Robert (Persistent Memory)
2018-11-27 20:23 ` Daniel Jordan
2018-11-19 16:29 ` Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 12/13] mm: parallelize clear_gigantic_page Daniel Jordan
2018-11-05 16:55 ` [RFC PATCH v4 13/13] hugetlbfs: parallelize hugetlbfs_fallocate with ktask Daniel Jordan
2018-11-05 17:29 ` [RFC PATCH v4 00/13] ktask: multithread CPU-intensive kernel work Michal Hocko
2018-11-06 1:29 ` Daniel Jordan
2018-11-06 9:21 ` Michal Hocko
2018-11-07 20:17 ` Daniel Jordan
2018-11-05 18:49 ` Zi Yan
2018-11-06 2:20 ` Daniel Jordan
2018-11-06 2:48 ` Zi Yan
2018-11-06 19:00 ` Daniel Jordan
2018-11-30 19:18 ` Tejun Heo
2018-12-01 0:13 ` Daniel Jordan
2018-12-03 16:16 ` Tejun Heo
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