On Thu, Aug 03, 2017 at 03:39:02PM -0700, Andrew Morton wrote:
>
> (cc Kirill)
>
> On Thu, 3 Aug 2017 12:35:28 -0400 axie <axie@xxxxxxx> wrote:
>
> > Hi Andrew,
> >
> >
> > I got a report yesterday with "BUG: sleeping function called from
> > invalid context at kernel/locking/mutex.c"
> >
> > I checked the relevant functions for the issue. Function
> > page_vma_mapped_walk did acquire spinlock. Later, in MMU notifier,
> > amdgpu_mn_invalidate_page called function mutex_lock, which triggered
> > the "bug".
> >
> > Function page_vma_mapped_walk was introduced recently by you in commit
> > c7ab0d2fdc840266b39db94538f74207ec2afbf6 and
> > ace71a19cec5eb430207c3269d8a2683f0574306.
> >
> > Would you advise how to proceed with this bug? Change
> > page_vma_mapped_walk not to use spinlock? Or change
> > amdgpu_mn_invalidate_page to use spinlock to meet the change, or
> > something else?
> >
>
> hm, as far as I can tell this was an unintended side-effect of
> c7ab0d2fd ("mm: convert try_to_unmap_one() to use
> page_vma_mapped_walk()"). Before that patch,
> mmu_notifier_invalidate_page() was not called under page_table_lock.
> After that patch, mmu_notifier_invalidate_page() is called under
> page_table_lock.
>
> Perhaps Kirill can suggest a fix?
Sorry for this.
What about the patch below?
>From f48dbcdd0ed83dee9a157062b7ca1e2915172678 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Fri, 4 Aug 2017 16:37:26 +0300
Subject: [PATCH] rmap: do not call mmu_notifier_invalidate_page() under ptl
MMU notifiers can sleep, but in page_mkclean_one() we call
mmu_notifier_invalidate_page() under page table lock.
Let's instead use mmu_notifier_invalidate_range() outside
page_vma_mapped_walk() loop.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Fixes: c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()")
---
mm/rmap.c | 21 +++++++++++++--------
1 file changed, 13 insertions(+), 8 deletions(-)
diff --git a/mm/rmap.c b/mm/rmap.c
index ced14f1af6dc..b4b711a82c01 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -852,10 +852,10 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
.flags = PVMW_SYNC,
};
int *cleaned = arg;
+ bool invalidation_needed = false;
while (page_vma_mapped_walk(&pvmw)) {
int ret = 0;
- address = pvmw.address;
if (pvmw.pte) {
pte_t entry;
pte_t *pte = pvmw.pte;
@@ -863,11 +863,11 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
if (!pte_dirty(*pte) && !pte_write(*pte))
continue;
- flush_cache_page(vma, address, pte_pfn(*pte));
- entry = ptep_clear_flush(vma, address, pte);
+ flush_cache_page(vma, pvmw.address, pte_pfn(*pte));
+ entry = ptep_clear_flush(vma, pvmw.address, pte);
entry = pte_wrprotect(entry);
entry = pte_mkclean(entry);
- set_pte_at(vma->vm_mm, address, pte, entry);
+ set_pte_at(vma->vm_mm, pvmw.address, pte, entry);
ret = 1;
} else {
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
@@ -877,11 +877,11 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
if (!pmd_dirty(*pmd) && !pmd_write(*pmd))
continue;
- flush_cache_page(vma, address, page_to_pfn(page));
- entry = pmdp_huge_clear_flush(vma, address, pmd);
+ flush_cache_page(vma, pvmw.address, page_to_pfn(page));
+ entry = pmdp_huge_clear_flush(vma, pvmw.address, pmd);
entry = pmd_wrprotect(entry);
entry = pmd_mkclean(entry);
- set_pmd_at(vma->vm_mm, address, pmd, entry);
+ set_pmd_at(vma->vm_mm, pvmw.address, pmd, entry);
ret = 1;
#else
/* unexpected pmd-mapped page? */
@@ -890,11 +890,16 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
}
if (ret) {
- mmu_notifier_invalidate_page(vma->vm_mm, address);
(*cleaned)++;
+ invalidation_needed = true;
}
}
+ if (invalidation_needed) {
+ mmu_notifier_invalidate_range(vma->vm_mm, address,
+ address + (1UL << compound_order(page)));
+ }
+
return true;
}
--
Kirill A. Shutemov
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