The patch titled
Subject: fork: copy mm's vm usage counters under mmap_sem
has been removed from the -mm tree. Its filename was
fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Subject: fork: copy mm's vm usage counters under mmap_sem
If a forking process has a thread calling (un)mmap (silly but still),
the child process may have some of its mm's vm usage counters (total_vm
and friends) screwed up, because currently they are copied from oldmm
w/o holding any locks (memcpy in dup_mm).
This patch moves the counters initialization to dup_mmap() to be called
under oldmm->mmap_sem, which eliminates any possibility of race.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN kernel/fork.c~fork-copy-mms-vm-usage-counters-under-mmap_sem kernel/fork.c
--- a/kernel/fork.c~fork-copy-mms-vm-usage-counters-under-mmap_sem
+++ a/kernel/fork.c
@@ -374,6 +374,11 @@ static int dup_mmap(struct mm_struct *mm
*/
down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
+ mm->total_vm = oldmm->total_vm;
+ mm->shared_vm = oldmm->shared_vm;
+ mm->exec_vm = oldmm->exec_vm;
+ mm->stack_vm = oldmm->stack_vm;
+
rb_link = &mm->mm_rb.rb_node;
rb_parent = NULL;
pprev = &mm->mmap;
_
Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are
origin.patch
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