summaryrefslogtreecommitdiff
path: root/mm/mlock.c
diff options
context:
space:
mode:
authorSimon Guo <wei.guo.simon@gmail.com>2016-10-07 16:59:40 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-12-13 09:21:33 +0100
commitaf70fc347ff2c0a331e79e7662537fe18df6c572 (patch)
tree904246c996a72cdd892578c8a138ebafbba17722 /mm/mlock.c
parent78b572c9e3a1b7edf46da17ad96a86110dd65fe8 (diff)
downloadlinux-artik7-af70fc347ff2c0a331e79e7662537fe18df6c572.tar.gz
linux-artik7-af70fc347ff2c0a331e79e7662537fe18df6c572.tar.bz2
linux-artik7-af70fc347ff2c0a331e79e7662537fe18df6c572.zip
mm: mlock: avoid increase mm->locked_vm on mlock() when already mlock2(,MLOCK_ONFAULT)
commit b155b4fde5bdde9fed439cd1f5ea07173df2ed31 upstream. When one vma was with flag VM_LOCKED|VM_LOCKONFAULT (by invoking mlock2(,MLOCK_ONFAULT)), it can again be populated with mlock() with VM_LOCKED flag only. There is a hole in mlock_fixup() which increase mm->locked_vm twice even the two operations are on the same vma and both with VM_LOCKED flags. The issue can be reproduced by following code: mlock2(p, 1024 * 64, MLOCK_ONFAULT); //VM_LOCKED|VM_LOCKONFAULT mlock(p, 1024 * 64); //VM_LOCKED Then check the increase VmLck field in /proc/pid/status(to 128k). When vma is set with different vm_flags, and the new vm_flags is with VM_LOCKED, it is not necessarily be a "new locked" vma. This patch corrects this bug by prevent mm->locked_vm from increment when old vm_flags is already VM_LOCKED. Link: http://lkml.kernel.org/r/1472554781-9835-3-git-send-email-wei.guo.simon@gmail.com Signed-off-by: Simon Guo <wei.guo.simon@gmail.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Alexey Klimov <klimov.linux@gmail.com> Cc: Eric B Munson <emunson@akamai.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Simon Guo <wei.guo.simon@gmail.com> Cc: Thierry Reding <treding@nvidia.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rafael David Tinoco <rafael.tinoco@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/mlock.c')
-rw-r--r--mm/mlock.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/mm/mlock.c b/mm/mlock.c
index 9d2e773f3a95..b03f160c1bdd 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -504,6 +504,7 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
int nr_pages;
int ret = 0;
int lock = !!(newflags & VM_LOCKED);
+ vm_flags_t old_flags = vma->vm_flags;
if (newflags == vma->vm_flags || (vma->vm_flags & VM_SPECIAL) ||
is_vm_hugetlb_page(vma) || vma == get_gate_vma(current->mm))
@@ -538,6 +539,8 @@ success:
nr_pages = (end - start) >> PAGE_SHIFT;
if (!lock)
nr_pages = -nr_pages;
+ else if (old_flags & VM_LOCKED)
+ nr_pages = 0;
mm->locked_vm += nr_pages;
/*