Hi Fengguang,
On Fri, Feb 14, 2014 at 09:04:50PM +0800, Fengguang Wu wrote:
...
> FYI, there are new smatch warnings show up in
>
> tree: git://git.cmpxchg.org/linux-mmotm.git master
> head: 0363f94bc1c9b81f23ee7d2446331eb288568ea7
> commit: 81272031cc2831a3d1abb3c681f1188aa36a1454 [97/220] pagewalk: remove argument hmask from hugetlb_entry()
>
> fs/proc/task_mmu.c:1042 pagemap_hugetlb() error: we previously assumed 'vma' could be null (see line 1037)
>
> vim +/vma +1042 fs/proc/task_mmu.c
>
> d9104d1c Cyrill Gorcunov 2013-09-11 1031 int flags2;
> 16fbdce6 Konstantin Khlebnikov 2012-05-10 1032 pagemap_entry_t pme;
> 81272031 Naoya Horiguchi 2014-02-13 1033 unsigned long hmask;
> 5dc37642 Naoya Horiguchi 2009-12-14 1034
> d9104d1c Cyrill Gorcunov 2013-09-11 1035 WARN_ON_ONCE(!vma);
> d9104d1c Cyrill Gorcunov 2013-09-11 1036
> d9104d1c Cyrill Gorcunov 2013-09-11 @1037 if (vma && (vma->vm_flags & VM_SOFTDIRTY))
> d9104d1c Cyrill Gorcunov 2013-09-11 1038 flags2 = __PM_SOFT_DIRTY;
> d9104d1c Cyrill Gorcunov 2013-09-11 1039 else
> d9104d1c Cyrill Gorcunov 2013-09-11 1040 flags2 = 0;
> d9104d1c Cyrill Gorcunov 2013-09-11 1041
> 21a2f342 Naoya Horiguchi 2014-02-13 @1042 hmask = huge_page_mask(hstate_vma(vma));
> 5dc37642 Naoya Horiguchi 2009-12-14 1043 for (; addr != end; addr += PAGE_SIZE) {
> 116354d1 Naoya Horiguchi 2010-04-06 1044 int offset = (addr & ~hmask) >> PAGE_SHIFT;
> d9104d1c Cyrill Gorcunov 2013-09-11 1045 huge_pte_to_pagemap_entry(&pme, pm, *pte, offset, flags2);
Thanks for reporting, here is a patch.
We never have NULL vma in pagemap_hugetlb(), I added the BUG_ON check.
Thanks,
Naoya Horiguchi
---
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Date: Fri, 14 Feb 2014 09:35:06 -0500
Subject: [PATCH] fs/proc/task_mmu.c: assume non-NULL vma in pagemap_hugetlb()
Fengguang reported smatch error about potential NULL pointer access.
In updated page table walker, we never run ->hugetlb_entry() callback
on the address without vma. This is because __walk_page_range() checks
it in advance. So we can assume non-NULL vma in pagemap_hugetlb().
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index f819d0d4a0e8..69aed7192254 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1032,9 +1032,9 @@ static int pagemap_hugetlb(pte_t *pte, unsigned long addr, unsigned long end,
pagemap_entry_t pme;
unsigned long hmask;
- WARN_ON_ONCE(!vma);
+ BUG_ON(!vma);
- if (vma && (vma->vm_flags & VM_SOFTDIRTY))
+ if (vma->vm_flags & VM_SOFTDIRTY)
flags2 = __PM_SOFT_DIRTY;
else
flags2 = 0;
--
1.8.5.3
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