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Date: Tue, 1 Sep 2015 04:54:40 +0800
From: Chen Gang <xili_gchen_5257@...mail.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
"mhocko@...e.cz" <mhocko@...e.cz>
CC: Linux Memory <linux-mm@...ck.org>,
kernel mailing list <linux-kernel@...r.kernel.org>
Subject: [PATCH] mm/mmap.c: Only call vma_unlock_anon_vm() when failure
occurs in expand_upwards() and expand_downwards()
When failure occurs, we need not call khugepaged_enter_vma_merge() or
validate_mm().
Also simplify do_munmap(): declare 'error' 1 time instead of 2 times in
sub-blocks.
Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>
---
mm/mmap.c | 116 +++++++++++++++++++++++++++++++-------------------------------
1 file changed, 58 insertions(+), 58 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index df6d5f0..d32199a 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2182,10 +2182,9 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
if (address < PAGE_ALIGN(address+4))
address = PAGE_ALIGN(address+4);
else {
- vma_unlock_anon_vma(vma);
- return -ENOMEM;
+ error = -ENOMEM;
+ goto err;
}
- error = 0;
/* Somebody else might have raced and expanded it already */
if (address> vma->vm_end) {
@@ -2194,38 +2193,39 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
size = address - vma->vm_start;
grow = (address - vma->vm_end)>> PAGE_SHIFT;
- error = -ENOMEM;
- if (vma->vm_pgoff + (size>> PAGE_SHIFT)>= vma->vm_pgoff) {
- error = acct_stack_growth(vma, size, grow);
- if (!error) {
- /*
- * vma_gap_update() doesn't support concurrent
- * updates, but we only hold a shared mmap_sem
- * lock here, so we need to protect against
- * concurrent vma expansions.
- * vma_lock_anon_vma() doesn't help here, as
- * we don't guarantee that all growable vmas
- * in a mm share the same root anon vma.
- * So, we reuse mm->page_table_lock to guard
- * against concurrent vma expansions.
- */
- spin_lock(&vma->vm_mm->page_table_lock);
- anon_vma_interval_tree_pre_update_vma(vma);
- vma->vm_end = address;
- anon_vma_interval_tree_post_update_vma(vma);
- if (vma->vm_next)
- vma_gap_update(vma->vm_next);
- else
- vma->vm_mm->highest_vm_end = address;
- spin_unlock(&vma->vm_mm->page_table_lock);
-
- perf_event_mmap(vma);
- }
+ if (vma->vm_pgoff + (size>> PAGE_SHIFT) < vma->vm_pgoff) {
+ error = -ENOMEM;
+ goto err;
}
+ error = acct_stack_growth(vma, size, grow);
+ if (error)
+ goto err;
+ /*
+ * vma_gap_update() doesn't support concurrent updates, but we
+ * only hold a shared mmap_sem lock here, so we need to protect
+ * against concurrent vma expansions. vma_lock_anon_vma()
+ * doesn't help here, as we don't guarantee that all growable
+ * vmas in a mm share the same root anon vma. So, we reuse mm->
+ * page_table_lock to guard against concurrent vma expansions.
+ */
+ spin_lock(&vma->vm_mm->page_table_lock);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ vma->vm_end = address;
+ anon_vma_interval_tree_post_update_vma(vma);
+ if (vma->vm_next)
+ vma_gap_update(vma->vm_next);
+ else
+ vma->vm_mm->highest_vm_end = address;
+ spin_unlock(&vma->vm_mm->page_table_lock);
+
+ perf_event_mmap(vma);
}
vma_unlock_anon_vma(vma);
khugepaged_enter_vma_merge(vma, vma->vm_flags);
validate_mm(vma->vm_mm);
+ return 0;
+err:
+ vma_unlock_anon_vma(vma);
return error;
}
#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
@@ -2265,36 +2265,37 @@ int expand_downwards(struct vm_area_struct *vma,
size = vma->vm_end - address;
grow = (vma->vm_start - address)>> PAGE_SHIFT;
- error = -ENOMEM;
- if (grow <= vma->vm_pgoff) {
- error = acct_stack_growth(vma, size, grow);
- if (!error) {
- /*
- * vma_gap_update() doesn't support concurrent
- * updates, but we only hold a shared mmap_sem
- * lock here, so we need to protect against
- * concurrent vma expansions.
- * vma_lock_anon_vma() doesn't help here, as
- * we don't guarantee that all growable vmas
- * in a mm share the same root anon vma.
- * So, we reuse mm->page_table_lock to guard
- * against concurrent vma expansions.
- */
- spin_lock(&vma->vm_mm->page_table_lock);
- anon_vma_interval_tree_pre_update_vma(vma);
- vma->vm_start = address;
- vma->vm_pgoff -= grow;
- anon_vma_interval_tree_post_update_vma(vma);
- vma_gap_update(vma);
- spin_unlock(&vma->vm_mm->page_table_lock);
-
- perf_event_mmap(vma);
- }
+ if (grow> vma->vm_pgoff) {
+ error = -ENOMEM;
+ goto err;
}
+ error = acct_stack_growth(vma, size, grow);
+ if (error)
+ goto err;
+ /*
+ * vma_gap_update() doesn't support concurrent updates, but we
+ * only hold a shared mmap_sem lock here, so we need to protect
+ * against concurrent vma expansions. vma_lock_anon_vma()
+ * doesn't help here, as we don't guarantee that all growable
+ * vmas in a mm share the same root anon vma. So, we reuse mm->
+ * page_table_lock to guard against concurrent vma expansions.
+ */
+ spin_lock(&vma->vm_mm->page_table_lock);
+ anon_vma_interval_tree_pre_update_vma(vma);
+ vma->vm_start = address;
+ vma->vm_pgoff -= grow;
+ anon_vma_interval_tree_post_update_vma(vma);
+ vma_gap_update(vma);
+ spin_unlock(&vma->vm_mm->page_table_lock);
+
+ perf_event_mmap(vma);
}
vma_unlock_anon_vma(vma);
khugepaged_enter_vma_merge(vma, vma->vm_flags);
validate_mm(vma->vm_mm);
+ return 0;
+err:
+ vma_unlock_anon_vma(vma);
return error;
}
@@ -2542,6 +2543,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
{
unsigned long end;
struct vm_area_struct *vma, *prev, *last;
+ int error;
if ((start & ~PAGE_MASK) || start> TASK_SIZE || len> TASK_SIZE-start)
return -EINVAL;
@@ -2570,8 +2572,6 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
* places tmp vma above, and higher split_vma places tmp vma below.
*/
if (start> vma->vm_start) {
- int error;
-
/*
* Make sure that map_count on return from munmap() will
* not exceed its limit; but let map_count go just above
@@ -2589,7 +2589,7 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
/* Does it split the last one? */
last = find_vma(mm, end);
if (last && end> last->vm_start) {
- int error = __split_vma(mm, last, end, 1);
+ error = __split_vma(mm, last, end, 1);
if (error)
return error;
}
--
1.9.3
--
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