From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com, Will Deacon <will@kernel.org>,
Yu Zhao <yuzhao@google.com>, Minchan Kim <minchan@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
Mohamed Alzayat <alzayat@mpi-sws.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
linux-mm@kvack.org
Subject: [PATCH v2 1/6] mm: proc: Invalidate TLB after clearing soft-dirty page state
Date: Thu, 10 Dec 2020 12:11:05 +0000 [thread overview]
Message-ID: <20201210121110.10094-2-will@kernel.org> (raw)
In-Reply-To: <20201210121110.10094-1-will@kernel.org>
Since commit 0758cd830494 ("asm-generic/tlb: avoid potential double
flush"), TLB invalidation is elided in tlb_finish_mmu() if no entries
were batched via the tlb_remove_*() functions. Consequently, the
page-table modifications performed by clear_refs_write() in response to
a write to /proc/<pid>/clear_refs do not perform TLB invalidation.
Although this is fine when simply aging the ptes, in the case of
clearing the "soft-dirty" state we can end up with entries where
pte_write() is false, yet a writable mapping remains in the TLB.
Fix this by avoiding the mmu_gather API altogether: managing both the
'tlb_flush_pending' flag on the 'mm_struct' and explicit TLB
invalidation for the sort-dirty path, much like mprotect() does already.
Signed-off-by: Will Deacon <will@kernel.org>
---
fs/proc/task_mmu.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 217aa2705d5d..132771edff7b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1189,7 +1189,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
struct mm_struct *mm;
struct vm_area_struct *vma;
enum clear_refs_types type;
- struct mmu_gather tlb;
int itype;
int rv;
@@ -1234,7 +1233,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
count = -EINTR;
goto out_mm;
}
- tlb_gather_mmu(&tlb, mm, 0, -1);
if (type == CLEAR_REFS_SOFT_DIRTY) {
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (!(vma->vm_flags & VM_SOFTDIRTY))
@@ -1252,15 +1250,18 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
break;
}
+ inc_tlb_flush_pending(mm);
mmu_notifier_range_init(&range, MMU_NOTIFY_SOFT_DIRTY,
0, NULL, mm, 0, -1UL);
mmu_notifier_invalidate_range_start(&range);
}
walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops,
&cp);
- if (type == CLEAR_REFS_SOFT_DIRTY)
+ if (type == CLEAR_REFS_SOFT_DIRTY) {
mmu_notifier_invalidate_range_end(&range);
- tlb_finish_mmu(&tlb, 0, -1);
+ flush_tlb_mm(mm);
+ dec_tlb_flush_pending(mm);
+ }
mmap_read_unlock(mm);
out_mm:
mmput(mm);
--
2.29.2.576.ga3fc446d84-goog
next prev parent reply other threads:[~2020-12-10 12:12 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-10 12:11 [PATCH v2 0/6] tlb: Fix (soft-)dirty bit management clean up API Will Deacon
2020-12-10 12:11 ` Will Deacon [this message]
2020-12-10 12:11 ` [PATCH v2 2/6] tlb: mmu_gather: Remove unused start/end arguments from tlb_finish_mmu() Will Deacon
2020-12-10 12:11 ` [PATCH v2 3/6] tlb: mmu_gather: Introduce tlb_gather_mmu_fullmm() Will Deacon
2020-12-10 23:44 ` Yu Zhao
2020-12-10 12:11 ` [PATCH v2 4/6] tlb: mmu_gather: Remove start/end arguments from tlb_gather_mmu() Will Deacon
2020-12-10 12:11 ` [PATCH v2 5/6] tlb: arch: Remove empty __tlb_remove_tlb_entry() stubs Will Deacon
2020-12-10 12:11 ` [PATCH v2 6/6] x86/ldt: Use tlb_gather_mmu_fullmm() when freeing LDT page-tables Will Deacon
2020-12-10 12:26 ` [PATCH v2 0/6] tlb: Fix (soft-)dirty bit management clean up API Peter Zijlstra
2020-12-17 11:50 ` Will Deacon
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