From: Will Deacon <will@kernel.org>
To: linux-kernel@vger.kernel.org
Cc: kernel-team@android.com, linux-mm@kvack.org,
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>,
Nadav Amit <namit@vmware.com>,
Andrea Arcangeli <aarcange@redhat.com>
Subject: [PATCH v3 1/6] mm: proc: Invalidate TLB after clearing soft-dirty page state
Date: Wed, 27 Jan 2021 23:53:42 +0000 [thread overview]
Message-ID: <20210127235347.1402-2-will@kernel.org> (raw)
In-Reply-To: <20210127235347.1402-1-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.
Fixes: 0758cd830494 ("asm-generic/tlb: avoid potential double flush”)
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yu Zhao <yuzhao@google.com>
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 602e3a52884d..3cec6fbef725 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1210,7 +1210,6 @@ 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;
@@ -1249,7 +1248,6 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
goto out_unlock;
}
- 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))
@@ -1258,15 +1256,18 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
vma_set_page_prot(vma);
}
+ 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);
+ }
out_unlock:
mmap_write_unlock(mm);
out_mm:
--
2.30.0.365.g02bc693789-goog
next prev parent reply other threads:[~2021-01-27 23:54 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 23:53 [PATCH v3 0/6] tlb: Fix (soft-)dirty bit management & clean up API Will Deacon
2021-01-27 23:53 ` Will Deacon [this message]
2021-01-27 23:53 ` [PATCH v3 2/6] tlb: mmu_gather: Remove unused start/end arguments from tlb_finish_mmu() Will Deacon
2021-01-27 23:53 ` [PATCH v3 3/6] tlb: mmu_gather: Introduce tlb_gather_mmu_fullmm() Will Deacon
2021-01-27 23:53 ` [PATCH v3 4/6] tlb: mmu_gather: Remove start/end arguments from tlb_gather_mmu() Will Deacon
2021-01-27 23:53 ` [PATCH v3 5/6] tlb: arch: Remove empty __tlb_remove_tlb_entry() stubs Will Deacon
2021-01-27 23:53 ` [PATCH v3 6/6] x86/ldt: Use tlb_gather_mmu_fullmm() when freeing LDT page-tables Will Deacon
2021-01-28 17:14 ` [PATCH v3 0/6] tlb: Fix (soft-)dirty bit management & clean up API Linus Torvalds
2021-01-29 11:09 ` Peter Zijlstra
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