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Subject[RFC PATCH] mm/rmap: do not call mmu_notifier_invalidate_page() v3
Date
Some MMU notifier need to be able to sleep during callback. This was
broken by c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use
page_vma_mapped_walk()").

This patch restore the sleep ability and properly capture the range of
address that needs to be invalidated.

Relevent threads:
https://lkml.kernel.org/r/20170809204333.27485-1-jglisse@redhat.com
https://lkml.kernel.org/r/20170804134928.l4klfcnqatni7vsc@black.fi.intel.com
https://marc.info/?l=kvm&m=150327081325160&w=2

Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Bernhard Held <berny156@gmx.de>
Cc: Adam Borowski <kilobyte@angband.pl>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Wanpeng Li <kernellwp@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: axie <axie@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
mm/rmap.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index c8993c63eb25..0b25b720f494 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -888,6 +888,8 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
.flags = PVMW_SYNC,
};
int *cleaned = arg;
+ bool invalidate = false;
+ unsigned long start = address, end = address;

while (page_vma_mapped_walk(&pvmw)) {
int ret = 0;
@@ -905,6 +907,9 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
entry = pte_mkclean(entry);
set_pte_at(vma->vm_mm, address, pte, entry);
ret = 1;
+ invalidate = true;
+ /* range is exclusive */
+ end = pvmw.address + PAGE_SIZE;
} else {
#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
pmd_t *pmd = pvmw.pmd;
@@ -919,18 +924,22 @@ static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma,
entry = pmd_mkclean(entry);
set_pmd_at(vma->vm_mm, address, pmd, entry);
ret = 1;
+ invalidate = true;
+ /* range is exclusive */
+ end = pvmw.address + PAGE_SIZE;
#else
/* unexpected pmd-mapped page? */
WARN_ON_ONCE(1);
#endif
}

- if (ret) {
- mmu_notifier_invalidate_page(vma->vm_mm, address);
+ if (ret)
(*cleaned)++;
- }
}

+ if (invalidate)
+ mmu_notifier_invalidate_range(vma->vm_mm, start, end);
+
return true;
}

@@ -1323,8 +1332,9 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
};
pte_t pteval;
struct page *subpage;
- bool ret = true;
+ bool ret = true, invalidate = false;
enum ttu_flags flags = (enum ttu_flags)arg;
+ unsigned long start = address, end = address;

/* munlock has nothing to gain from examining un-locked vmas */
if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
@@ -1490,8 +1500,14 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
discard:
page_remove_rmap(subpage, PageHuge(page));
put_page(page);
- mmu_notifier_invalidate_page(mm, address);
+ invalidate = true;
+ /* range is exclusive */
+ end = address + PAGE_SIZE;
}
+
+ if (invalidate)
+ mmu_notifier_invalidate_range(mm, start, end);
+
return ret;
}

--
2.13.5
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