[PATCH] mm: remove zap_page_range and create zap_vma_pages

From: Mike Kravetz
Date: Tue Jan 03 2023 - 19:31:08 EST

zap_page_range was originally designed to unmap pages within an address
range that could span multiple vmas. While working on [1], it was
discovered that all callers of zap_page_range pass a range entirely within
a single vma. In addition, the mmu notification call within zap_page
range does not correctly handle ranges that span multiple vmas. When
crossing a vma boundary, a new mmu_notifier_range_init/end call pair
with the new vma should be made.

Instead of fixing zap_page_range, do the following:
- Create a new routine zap_vma_pages() that will remove all pages within
the passed vma. Most users of zap_page_range pass the entire vma and
can use this new routine.
- For callers of zap_page_range not passing the entire vma, instead call
zap_page_range_single().
- Remove zap_page_range.

[1] https://lore.kernel.org/linux-mm/20221114235507.294320-2-mike.kravetz@xxxxxxxxxx/
Suggested-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
---
RFC->v1 Created zap_vma_pages to zap entire vma (Christoph Hellwig)
Did not add Acked-by's as routine was changed.

arch/arm64/kernel/vdso.c | 6 ++---
arch/powerpc/kernel/vdso.c | 4 +---
arch/powerpc/platforms/book3s/vas-api.c | 2 +-
arch/powerpc/platforms/pseries/vas.c | 3 +--
arch/riscv/kernel/vdso.c | 6 ++---
arch/s390/kernel/vdso.c | 4 +---
arch/s390/mm/gmap.c | 2 +-
arch/x86/entry/vdso/vma.c | 4 +---
drivers/android/binder_alloc.c | 2 +-
include/linux/mm.h | 7 ++++--
mm/memory.c | 30 -------------------------
mm/page-writeback.c | 2 +-
net/ipv4/tcp.c | 7 +++---
13 files changed, 21 insertions(+), 58 deletions(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index e59a32aa0c49..0119dc91abb5 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -138,13 +138,11 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
mmap_read_lock(mm);

for_each_vma(vmi, vma) {
- unsigned long size = vma->vm_end - vma->vm_start;
-
if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA64].dm))
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
#ifdef CONFIG_COMPAT_VDSO
if (vma_is_special_mapping(vma, vdso_info[VDSO_ABI_AA32].dm))
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
#endif
}

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 507f8228f983..7a2ff9010f17 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -120,10 +120,8 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)

mmap_read_lock(mm);
for_each_vma(vmi, vma) {
- unsigned long size = vma->vm_end - vma->vm_start;
-
if (vma_is_special_mapping(vma, &vvar_spec))
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
}
mmap_read_unlock(mm);

diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c
index eb5bed333750..9580e8e12165 100644
--- a/arch/powerpc/platforms/book3s/vas-api.c
+++ b/arch/powerpc/platforms/book3s/vas-api.c
@@ -414,7 +414,7 @@ static vm_fault_t vas_mmap_fault(struct vm_fault *vmf)
/*
* When the LPAR lost credits due to core removal or during
* migration, invalidate the existing mapping for the current
- * paste addresses and set windows in-active (zap_page_range in
+ * paste addresses and set windows in-active (zap_vma_pages in
* reconfig_close_windows()).
* New mapping will be done later after migration or new credits
* available. So continue to receive faults if the user space
diff --git a/arch/powerpc/platforms/pseries/vas.c b/arch/powerpc/platforms/pseries/vas.c
index 4ad6e510d405..559112312810 100644
--- a/arch/powerpc/platforms/pseries/vas.c
+++ b/arch/powerpc/platforms/pseries/vas.c
@@ -760,8 +760,7 @@ static int reconfig_close_windows(struct vas_caps *vcap, int excess_creds,
* is done before the original mmap() and after the ioctl.
*/
if (vma)
- zap_page_range(vma, vma->vm_start,
- vma->vm_end - vma->vm_start);
+ zap_vma_pages(vma);

mmap_write_unlock(task_ref->mm);
mutex_unlock(&task_ref->mmap_mutex);
diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c
index e410275918ac..5c30212d8d1c 100644
--- a/arch/riscv/kernel/vdso.c
+++ b/arch/riscv/kernel/vdso.c
@@ -124,13 +124,11 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
mmap_read_lock(mm);

for_each_vma(vmi, vma) {
- unsigned long size = vma->vm_end - vma->vm_start;
-
if (vma_is_special_mapping(vma, vdso_info.dm))
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
#ifdef CONFIG_COMPAT
if (vma_is_special_mapping(vma, compat_vdso_info.dm))
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
#endif
}

diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c
index ff7bf4432229..bbaefd84f15e 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -59,11 +59,9 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)

mmap_read_lock(mm);
for_each_vma(vmi, vma) {
- unsigned long size = vma->vm_end - vma->vm_start;
-
if (!vma_is_special_mapping(vma, &vvar_mapping))
continue;
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
break;
}
mmap_read_unlock(mm);
diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 74e1d873dce0..69af6cdf1a2a 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -722,7 +722,7 @@ void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
if (is_vm_hugetlb_page(vma))
continue;
size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
- zap_page_range(vma, vmaddr, size);
+ zap_page_range_single(vma, vmaddr, size, NULL);
}
mmap_read_unlock(gmap->mm);
}
diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index b8f3f9b9e53c..ec5e4d2048cb 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -113,10 +113,8 @@ int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)

mmap_read_lock(mm);
for_each_vma(vmi, vma) {
- unsigned long size = vma->vm_end - vma->vm_start;
-
if (vma_is_special_mapping(vma, &vvar_mapping))
- zap_page_range(vma, vma->vm_start, size);
+ zap_vma_pages(vma);
}
mmap_read_unlock(mm);

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index 4ad42b0f75cd..55a3c3c2409f 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -1019,7 +1019,7 @@ enum lru_status binder_alloc_free_page(struct list_head *item,
if (vma) {
trace_binder_unmap_user_start(alloc, index);

- zap_page_range(vma, page_addr, PAGE_SIZE);
+ zap_page_range_single(vma, page_addr, PAGE_SIZE, NULL);

trace_binder_unmap_user_end(alloc, index);
}
diff --git a/include/linux/mm.h b/include/linux/mm.h
index c1ea18bc99e2..e4374baadbf3 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1977,10 +1977,13 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,

void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
unsigned long size);
-void zap_page_range(struct vm_area_struct *vma, unsigned long address,
- unsigned long size);
void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
unsigned long size, struct zap_details *details);
+static inline void zap_vma_pages(struct vm_area_struct *vma)
+{
+ zap_page_range_single(vma, vma->vm_start,
+ vma->vm_end - vma->vm_start, NULL);
+}
void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
struct vm_area_struct *start_vma, unsigned long start,
unsigned long end);
diff --git a/mm/memory.c b/mm/memory.c
index 4000e9f017e0..14e63e14adc4 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1693,36 +1693,6 @@ void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,
mmu_notifier_invalidate_range_end(&range);
}

-/**
- * zap_page_range - remove user pages in a given range
- * @vma: vm_area_struct holding the applicable pages
- * @start: starting address of pages to zap
- * @size: number of bytes to zap
- *
- * Caller must protect the VMA list
- */
-void zap_page_range(struct vm_area_struct *vma, unsigned long start,
- unsigned long size)
-{
- struct maple_tree *mt = &vma->vm_mm->mm_mt;
- unsigned long end = start + size;
- struct mmu_notifier_range range;
- struct mmu_gather tlb;
- MA_STATE(mas, mt, vma->vm_end, vma->vm_end);
-
- lru_add_drain();
- mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm,
- start, start + size);
- tlb_gather_mmu(&tlb, vma->vm_mm);
- update_hiwater_rss(vma->vm_mm);
- mmu_notifier_invalidate_range_start(&range);
- do {
- unmap_single_vma(&tlb, vma, start, range.end, NULL);
- } while ((vma = mas_find(&mas, end - 1)) != NULL);
- mmu_notifier_invalidate_range_end(&range);
- tlb_finish_mmu(&tlb);
-}
-
/**
* zap_page_range_single - remove user pages in a given range
* @vma: vm_area_struct holding the applicable pages
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index ad608ef2a243..ffa36cfe5884 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2713,7 +2713,7 @@ void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb)
*
* The caller must hold lock_page_memcg(). Most callers have the folio
* locked. A few have the folio blocked from truncation through other
- * means (eg zap_page_range() has it mapped and is holding the page table
+ * means (eg zap_vma_pages() has it mapped and is holding the page table
* lock). This can also be called from mark_buffer_dirty(), which I
* cannot prove is always protected against truncate.
*/
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c567d5e8053e..f713c0422f0f 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2092,7 +2092,7 @@ static int tcp_zerocopy_vm_insert_batch_error(struct vm_area_struct *vma,
maybe_zap_len = total_bytes_to_map - /* All bytes to map */
*length + /* Mapped or pending */
(pages_remaining * PAGE_SIZE); /* Failed map. */
- zap_page_range(vma, *address, maybe_zap_len);
+ zap_page_range_single(vma, *address, maybe_zap_len, NULL);
err = 0;
}

@@ -2100,7 +2100,7 @@ static int tcp_zerocopy_vm_insert_batch_error(struct vm_area_struct *vma,
unsigned long leftover_pages = pages_remaining;
int bytes_mapped;

- /* We called zap_page_range, try to reinsert. */
+ /* We called zap_page_range_single, try to reinsert. */
err = vm_insert_pages(vma, *address,
pending_pages,
&pages_remaining);
@@ -2234,7 +2234,8 @@ static int tcp_zerocopy_receive(struct sock *sk,
total_bytes_to_map = avail_len & ~(PAGE_SIZE - 1);
if (total_bytes_to_map) {
if (!(zc->flags & TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT))
- zap_page_range(vma, address, total_bytes_to_map);
+ zap_page_range_single(vma, address, total_bytes_to_map,
+ NULL);
zc->length = total_bytes_to_map;
zc->recv_skip_hint = 0;
} else {
--
2.38.1