* [PATCH] mm: softdirty: addresses before VMAs in PTE holes aren't softdirty
@ 2014-09-10 18:34 ` Peter Feiner
0 siblings, 0 replies; 4+ messages in thread
From: Peter Feiner @ 2014-09-10 18:34 UTC (permalink / raw)
To: linux-mm
Cc: linux-kernel, Peter Feiner, Kirill A. Shutemov, Cyrill Gorcunov,
Pavel Emelyanov, Jamie Liu, Hugh Dickins, Naoya Horiguchi,
Andrew Morton
In PTE holes that contain VM_SOFTDIRTY VMAs, unmapped addresses before
VM_SOFTDIRTY VMAs are reported as softdirty by /proc/pid/pagemap. This
bug was introduced in 68b5a652485682f67eacdee3deae640fb7845b63. The
aforementioned patch made /proc/pid/pagemap look at VM_SOFTDIRTY in PTE
holes but neglected to observe the start of VMAs returned by find_vma.
Tested:
Wrote a selftest that creates a PMD-sized VMA then unmaps the first
page and asserts that the page is not softdirty. I'm going to send the
pagemap selftest in a later commit.
Signed-off-by: Peter Feiner <pfeiner@google.com>
---
fs/proc/task_mmu.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index dfc791c..256dbe9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -931,16 +931,26 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
while (addr < end) {
struct vm_area_struct *vma = find_vma(walk->mm, addr);
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
- unsigned long vm_end;
+ unsigned long vm_start = end;
+ unsigned long vm_end = end;
+ unsigned long vm_flags = 0;
- if (!vma) {
- vm_end = end;
- } else {
+ if (vma) {
+ vm_start = min(end, vma->vm_start);
vm_end = min(end, vma->vm_end);
- if (vma->vm_flags & VM_SOFTDIRTY)
- pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
+ vm_flags = vma->vm_flags;
+ }
+
+ /* Addresses before the VMA. */
+ for (; addr < vm_start; addr += PAGE_SIZE) {
+ err = add_to_pagemap(addr, &pme, pm);
+ if (err)
+ goto out;
}
+ /* Addresses in the VMA. */
+ if (vm_flags & VM_SOFTDIRTY)
+ pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
for (; addr < vm_end; addr += PAGE_SIZE) {
err = add_to_pagemap(addr, &pme, pm);
if (err)
--
2.1.0.rc2.206.gedb03e5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH] mm: softdirty: addresses before VMAs in PTE holes aren't softdirty
@ 2014-09-10 18:34 ` Peter Feiner
0 siblings, 0 replies; 4+ messages in thread
From: Peter Feiner @ 2014-09-10 18:34 UTC (permalink / raw)
To: linux-mm
Cc: linux-kernel, Peter Feiner, Kirill A. Shutemov, Cyrill Gorcunov,
Pavel Emelyanov, Jamie Liu, Hugh Dickins, Naoya Horiguchi,
Andrew Morton
In PTE holes that contain VM_SOFTDIRTY VMAs, unmapped addresses before
VM_SOFTDIRTY VMAs are reported as softdirty by /proc/pid/pagemap. This
bug was introduced in 68b5a652485682f67eacdee3deae640fb7845b63. The
aforementioned patch made /proc/pid/pagemap look at VM_SOFTDIRTY in PTE
holes but neglected to observe the start of VMAs returned by find_vma.
Tested:
Wrote a selftest that creates a PMD-sized VMA then unmaps the first
page and asserts that the page is not softdirty. I'm going to send the
pagemap selftest in a later commit.
Signed-off-by: Peter Feiner <pfeiner@google.com>
---
fs/proc/task_mmu.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index dfc791c..256dbe9 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -931,16 +931,26 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
while (addr < end) {
struct vm_area_struct *vma = find_vma(walk->mm, addr);
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
- unsigned long vm_end;
+ unsigned long vm_start = end;
+ unsigned long vm_end = end;
+ unsigned long vm_flags = 0;
- if (!vma) {
- vm_end = end;
- } else {
+ if (vma) {
+ vm_start = min(end, vma->vm_start);
vm_end = min(end, vma->vm_end);
- if (vma->vm_flags & VM_SOFTDIRTY)
- pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
+ vm_flags = vma->vm_flags;
+ }
+
+ /* Addresses before the VMA. */
+ for (; addr < vm_start; addr += PAGE_SIZE) {
+ err = add_to_pagemap(addr, &pme, pm);
+ if (err)
+ goto out;
}
+ /* Addresses in the VMA. */
+ if (vm_flags & VM_SOFTDIRTY)
+ pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
for (; addr < vm_end; addr += PAGE_SIZE) {
err = add_to_pagemap(addr, &pme, pm);
if (err)
--
2.1.0.rc2.206.gedb03e5
--
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^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2] mm: softdirty: addresses before VMAs in PTE holes aren't softdirty
2014-09-10 18:34 ` Peter Feiner
@ 2014-09-15 19:19 ` Peter Feiner
-1 siblings, 0 replies; 4+ messages in thread
From: Peter Feiner @ 2014-09-15 19:19 UTC (permalink / raw)
To: linux-mm
Cc: linux-kernel, Peter Feiner, Kirill A. Shutemov, Cyrill Gorcunov,
Pavel Emelyanov, Jamie Liu, Hugh Dickins, Naoya Horiguchi,
Andrew Morton
In PTE holes that contain VM_SOFTDIRTY VMAs, unmapped addresses before
VM_SOFTDIRTY VMAs are reported as softdirty by /proc/pid/pagemap. This
bug was introduced in 68b5a652485682f67eacdee3deae640fb7845b63. The
aforementioned patch made /proc/pid/pagemap look at VM_SOFTDIRTY in PTE
holes but neglected to observe the start of VMAs returned by find_vma.
Tested:
Wrote a selftest that creates a PMD-sized VMA then unmaps the first
page and asserts that the page is not softdirty. I'm going to send the
pagemap selftest in a later commit.
Signed-off-by: Peter Feiner <pfeiner@google.com>
---
v1 -> v2:
Rewrote to make logic easier to follow.
---
fs/proc/task_mmu.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index dfc791c..c341568 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -931,23 +931,32 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
while (addr < end) {
struct vm_area_struct *vma = find_vma(walk->mm, addr);
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
- unsigned long vm_end;
+ /* End of address space hole, which we mark as non-present. */
+ unsigned long hole_end;
- if (!vma) {
- vm_end = end;
- } else {
- vm_end = min(end, vma->vm_end);
- if (vma->vm_flags & VM_SOFTDIRTY)
- pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
+ if (vma)
+ hole_end = min(end, vma->vm_start);
+ else
+ hole_end = end;
+
+ for (; addr < hole_end; addr += PAGE_SIZE) {
+ err = add_to_pagemap(addr, &pme, pm);
+ if (err)
+ goto out;
}
- for (; addr < vm_end; addr += PAGE_SIZE) {
+ if (!vma)
+ break;
+
+ /* Addresses in the VMA. */
+ if (vma->vm_flags & VM_SOFTDIRTY)
+ pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
+ for (; addr < min(end, vma->vm_end); addr += PAGE_SIZE) {
err = add_to_pagemap(addr, &pme, pm);
if (err)
goto out;
}
}
-
out:
return err;
}
--
2.1.0.rc2.206.gedb03e5
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v2] mm: softdirty: addresses before VMAs in PTE holes aren't softdirty
@ 2014-09-15 19:19 ` Peter Feiner
0 siblings, 0 replies; 4+ messages in thread
From: Peter Feiner @ 2014-09-15 19:19 UTC (permalink / raw)
To: linux-mm
Cc: linux-kernel, Peter Feiner, Kirill A. Shutemov, Cyrill Gorcunov,
Pavel Emelyanov, Jamie Liu, Hugh Dickins, Naoya Horiguchi,
Andrew Morton
In PTE holes that contain VM_SOFTDIRTY VMAs, unmapped addresses before
VM_SOFTDIRTY VMAs are reported as softdirty by /proc/pid/pagemap. This
bug was introduced in 68b5a652485682f67eacdee3deae640fb7845b63. The
aforementioned patch made /proc/pid/pagemap look at VM_SOFTDIRTY in PTE
holes but neglected to observe the start of VMAs returned by find_vma.
Tested:
Wrote a selftest that creates a PMD-sized VMA then unmaps the first
page and asserts that the page is not softdirty. I'm going to send the
pagemap selftest in a later commit.
Signed-off-by: Peter Feiner <pfeiner@google.com>
---
v1 -> v2:
Rewrote to make logic easier to follow.
---
fs/proc/task_mmu.c | 27 ++++++++++++++++++---------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index dfc791c..c341568 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -931,23 +931,32 @@ static int pagemap_pte_hole(unsigned long start, unsigned long end,
while (addr < end) {
struct vm_area_struct *vma = find_vma(walk->mm, addr);
pagemap_entry_t pme = make_pme(PM_NOT_PRESENT(pm->v2));
- unsigned long vm_end;
+ /* End of address space hole, which we mark as non-present. */
+ unsigned long hole_end;
- if (!vma) {
- vm_end = end;
- } else {
- vm_end = min(end, vma->vm_end);
- if (vma->vm_flags & VM_SOFTDIRTY)
- pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
+ if (vma)
+ hole_end = min(end, vma->vm_start);
+ else
+ hole_end = end;
+
+ for (; addr < hole_end; addr += PAGE_SIZE) {
+ err = add_to_pagemap(addr, &pme, pm);
+ if (err)
+ goto out;
}
- for (; addr < vm_end; addr += PAGE_SIZE) {
+ if (!vma)
+ break;
+
+ /* Addresses in the VMA. */
+ if (vma->vm_flags & VM_SOFTDIRTY)
+ pme.pme |= PM_STATUS2(pm->v2, __PM_SOFT_DIRTY);
+ for (; addr < min(end, vma->vm_end); addr += PAGE_SIZE) {
err = add_to_pagemap(addr, &pme, pm);
if (err)
goto out;
}
}
-
out:
return err;
}
--
2.1.0.rc2.206.gedb03e5
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2014-09-15 19:19 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2014-09-10 18:34 [PATCH] mm: softdirty: addresses before VMAs in PTE holes aren't softdirty Peter Feiner
2014-09-10 18:34 ` Peter Feiner
2014-09-15 19:19 ` [PATCH v2] " Peter Feiner
2014-09-15 19:19 ` Peter Feiner
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