From: Pengfei Li <fly@kernel.page>
To: akpm@linux-foundation.org
Cc: bmt@zurich.ibm.com, dledford@redhat.com, willy@infradead.org,
vbabka@suse.cz, kirill.shutemov@linux.intel.com, jgg@ziepe.ca,
alex.williamson@redhat.com, cohuck@redhat.com,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Pengfei Li <fly@kernel.page>
Subject: [PATCH 2/2] mm, util: account_locked_vm() does not hold mmap_lock
Date: Sun, 26 Jul 2020 16:02:24 +0800 [thread overview]
Message-ID: <20200726080224.205470-2-fly@kernel.page> (raw)
In-Reply-To: <20200726080224.205470-1-fly@kernel.page>
Since mm->locked_vm is already an atomic counter, account_locked_vm()
does not need to hold mmap_lock.
Signed-off-by: Pengfei Li <fly@kernel.page>
---
drivers/vfio/vfio_iommu_type1.c | 8 ++------
mm/util.c | 15 +++------------
2 files changed, 5 insertions(+), 18 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 78013be07fe7..53818fce78a6 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -376,12 +376,8 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
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);
diff --git a/mm/util.c b/mm/util.c
index 473add0dc275..320fdd537aea 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -424,8 +424,7 @@ void arch_pick_mmap_layout(struct mm_struct *mm, struct rlimit *rlim_stack)
* @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 *mm, unsigned long pages, bool inc,
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);
--
2.26.2
next prev parent reply other threads:[~2020-07-26 8:03 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-26 8:02 [PATCH 1/2] mm: make mm->locked_vm an atomic64 counter Pengfei Li
2020-07-26 8:02 ` Pengfei Li [this message]
2020-07-29 19:21 ` [PATCH 2/2] mm, util: account_locked_vm() does not hold mmap_lock Hugh Dickins
2020-07-30 20:57 ` Daniel Jordan
2020-08-02 11:23 ` Pengfei Li
2020-08-02 11:07 ` Pengfei Li
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200726080224.205470-2-fly@kernel.page \
--to=fly@kernel.page \
--cc=akpm@linux-foundation.org \
--cc=alex.williamson@redhat.com \
--cc=bmt@zurich.ibm.com \
--cc=cohuck@redhat.com \
--cc=dledford@redhat.com \
--cc=jgg@ziepe.ca \
--cc=kirill.shutemov@linux.intel.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).