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Subject[PATCH 1/2] mm: make mm->locked_vm an atomic64 counter
Date
Like commit 70f8a3ca68d3 ("mm: make mm->pinned_vm an atomic64 counter").

By making mm->locked_vm an atomic64 counter, we can safely modify it
without holding mmap_lock.

The reason for using atomic64 instead of atomic_long is to keep the same
as mm->pinned_vm, and there is no need to worry about overflow.

Signed-off-by: Pengfei Li <fly@kernel.page>
---
drivers/infiniband/sw/siw/siw_verbs.c | 12 +++++++-----
drivers/vfio/vfio_iommu_type1.c | 6 ++++--
fs/io_uring.c | 4 ++--
fs/proc/task_mmu.c | 2 +-
include/linux/mm_types.h | 4 ++--
kernel/fork.c | 2 +-
mm/debug.c | 5 +++--
mm/mlock.c | 4 ++--
mm/mmap.c | 18 +++++++++---------
mm/mremap.c | 6 +++---
mm/util.c | 6 +++---
11 files changed, 37 insertions(+), 32 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_verbs.c b/drivers/infiniband/sw/siw/siw_verbs.c
index adafa1b8bebe..bf78d7988442 100644
--- a/drivers/infiniband/sw/siw/siw_verbs.c
+++ b/drivers/infiniband/sw/siw/siw_verbs.c
@@ -1293,14 +1293,16 @@ struct ib_mr *siw_reg_user_mr(struct ib_pd *pd, u64 start, u64 len,
goto err_out;
}
if (mem_limit != RLIM_INFINITY) {
- unsigned long num_pages =
- (PAGE_ALIGN(len + (start & ~PAGE_MASK))) >> PAGE_SHIFT;
+ unsigned long num_pages, locked_pages;
+
+ num_pages = (PAGE_ALIGN(len + (start & ~PAGE_MASK)))
+ >> PAGE_SHIFT;
+ locked_pages = atomic64_read(&current->mm->locked_vm);
mem_limit >>= PAGE_SHIFT;

- if (num_pages > mem_limit - current->mm->locked_vm) {
+ if (num_pages > mem_limit - locked_pages) {
siw_dbg_pd(pd, "pages req %lu, max %lu, lock %lu\n",
- num_pages, mem_limit,
- current->mm->locked_vm);
+ num_pages, mem_limit, locked_pages);
rv = -ENOMEM;
goto err_out;
}
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 9d41105bfd01..78013be07fe7 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -509,7 +509,8 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
* pages are already counted against the user.
*/
if (!rsvd && !vfio_find_vpfn(dma, iova)) {
- if (!dma->lock_cap && current->mm->locked_vm + 1 > limit) {
+ if (!dma->lock_cap &&
+ atomic64_read(&current->mm->locked_vm) + 1 > limit) {
put_pfn(*pfn_base, dma->prot);
pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__,
limit << PAGE_SHIFT);
@@ -536,7 +537,8 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,

if (!rsvd && !vfio_find_vpfn(dma, iova)) {
if (!dma->lock_cap &&
- current->mm->locked_vm + lock_acct + 1 > limit) {
+ atomic64_read(&current->mm->locked_vm) +
+ lock_acct + 1 > limit) {
put_pfn(pfn, dma->prot);
pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
__func__, limit << PAGE_SHIFT);
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 7cf2f295fba7..f1241c6314e6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -7371,7 +7371,7 @@ static void io_unaccount_mem(struct io_ring_ctx *ctx, unsigned long nr_pages,

if (ctx->sqo_mm) {
if (acct == ACCT_LOCKED)
- ctx->sqo_mm->locked_vm -= nr_pages;
+ atomic64_sub(nr_pages, &ctx->sqo_mm->locked_vm);
else if (acct == ACCT_PINNED)
atomic64_sub(nr_pages, &ctx->sqo_mm->pinned_vm);
}
@@ -7390,7 +7390,7 @@ static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages,

if (ctx->sqo_mm) {
if (acct == ACCT_LOCKED)
- ctx->sqo_mm->locked_vm += nr_pages;
+ atomic64_add(nr_pages, &ctx->sqo_mm->locked_vm);
else if (acct == ACCT_PINNED)
atomic64_add(nr_pages, &ctx->sqo_mm->pinned_vm);
}
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index df2f0f05f5ba..2af56e68766e 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -58,7 +58,7 @@ void task_mem(struct seq_file *m, struct mm_struct *mm)
swap = get_mm_counter(mm, MM_SWAPENTS);
SEQ_PUT_DEC("VmPeak:\t", hiwater_vm);
SEQ_PUT_DEC(" kB\nVmSize:\t", total_vm);
- SEQ_PUT_DEC(" kB\nVmLck:\t", mm->locked_vm);
+ SEQ_PUT_DEC(" kB\nVmLck:\t", atomic64_read(&mm->locked_vm));
SEQ_PUT_DEC(" kB\nVmPin:\t", atomic64_read(&mm->pinned_vm));
SEQ_PUT_DEC(" kB\nVmHWM:\t", hiwater_rss);
SEQ_PUT_DEC(" kB\nVmRSS:\t", total_rss);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 496c3ff97cce..3f0ad38c534d 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -457,8 +457,8 @@ struct mm_struct {
unsigned long hiwater_vm; /* High-water virtual memory usage */

unsigned long total_vm; /* Total pages mapped */
- unsigned long locked_vm; /* Pages that have PG_mlocked set */
- atomic64_t pinned_vm; /* Refcount permanently increased */
+ atomic64_t locked_vm; /* Pages that have PG_mlocked set */
+ atomic64_t pinned_vm; /* Refcount permanently increased */
unsigned long data_vm; /* VM_WRITE & ~VM_SHARED & ~VM_STACK */
unsigned long exec_vm; /* VM_EXEC & ~VM_WRITE & ~VM_STACK */
unsigned long stack_vm; /* VM_STACK */
diff --git a/kernel/fork.c b/kernel/fork.c
index 45cdf724a2d4..8ed0d0574621 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1009,7 +1009,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
mm->core_state = NULL;
mm_pgtables_bytes_init(mm);
mm->map_count = 0;
- mm->locked_vm = 0;
+ atomic64_set(&mm->locked_vm, 0);
atomic64_set(&mm->pinned_vm, 0);
memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
spin_lock_init(&mm->page_table_lock);
diff --git a/mm/debug.c b/mm/debug.c
index 8f569db9a514..c27fff1e3ca8 100644
--- a/mm/debug.c
+++ b/mm/debug.c
@@ -218,7 +218,7 @@ void dump_mm(const struct mm_struct *mm)
#endif
"mmap_base %lu mmap_legacy_base %lu highest_vm_end %lu\n"
"pgd %px mm_users %d mm_count %d pgtables_bytes %lu map_count %d\n"
- "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %lx\n"
+ "hiwater_rss %lx hiwater_vm %lx total_vm %lx locked_vm %llx\n"
"pinned_vm %llx data_vm %lx exec_vm %lx stack_vm %lx\n"
"start_code %lx end_code %lx start_data %lx end_data %lx\n"
"start_brk %lx brk %lx start_stack %lx\n"
@@ -249,7 +249,8 @@ void dump_mm(const struct mm_struct *mm)
atomic_read(&mm->mm_count),
mm_pgtables_bytes(mm),
mm->map_count,
- mm->hiwater_rss, mm->hiwater_vm, mm->total_vm, mm->locked_vm,
+ mm->hiwater_rss, mm->hiwater_vm, mm->total_vm,
+ (u64)atomic64_read(&mm->locked_vm),
(u64)atomic64_read(&mm->pinned_vm),
mm->data_vm, mm->exec_vm, mm->stack_vm,
mm->start_code, mm->end_code, mm->start_data, mm->end_data,
diff --git a/mm/mlock.c b/mm/mlock.c
index 93ca2bf30b4f..ec8c563ce233 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -561,7 +561,7 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
nr_pages = -nr_pages;
else if (old_flags & VM_LOCKED)
nr_pages = 0;
- mm->locked_vm += nr_pages;
+ atomic64_add(nr_pages, &mm->locked_vm);

/*
* vm_flags is protected by the mmap_lock held in write mode.
@@ -688,7 +688,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
if (mmap_write_lock_killable(current->mm))
return -EINTR;

- locked += current->mm->locked_vm;
+ locked += atomic64_read(&current->mm->locked_vm);
if ((locked > lock_limit) && (!capable(CAP_IPC_LOCK))) {
/*
* It is possible that the regions requested intersect with
diff --git a/mm/mmap.c b/mm/mmap.c
index c65bd5a7f80b..17bd229f820b 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1319,7 +1319,7 @@ static inline int mlock_future_check(struct mm_struct *mm,
/* mlock MCL_FUTURE? */
if (flags & VM_LOCKED) {
locked = len >> PAGE_SHIFT;
- locked += mm->locked_vm;
+ locked += atomic64_read(&mm->locked_vm);
lock_limit = rlimit(RLIMIT_MEMLOCK);
lock_limit >>= PAGE_SHIFT;
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
@@ -1812,7 +1812,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
vma == get_gate_vma(current->mm))
vma->vm_flags &= VM_LOCKED_CLEAR_MASK;
else
- mm->locked_vm += (len >> PAGE_SHIFT);
+ atomic64_add(len >> PAGE_SHIFT, &mm->locked_vm);
}

if (file)
@@ -2323,7 +2323,7 @@ static int acct_stack_growth(struct vm_area_struct *vma,
if (vma->vm_flags & VM_LOCKED) {
unsigned long locked;
unsigned long limit;
- locked = mm->locked_vm + grow;
+ locked = atomic64_read(&mm->locked_vm) + grow;
limit = rlimit(RLIMIT_MEMLOCK);
limit >>= PAGE_SHIFT;
if (locked > limit && !capable(CAP_IPC_LOCK))
@@ -2416,7 +2416,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
*/
spin_lock(&mm->page_table_lock);
if (vma->vm_flags & VM_LOCKED)
- mm->locked_vm += grow;
+ atomic64_add(grow, &mm->locked_vm);
vm_stat_account(mm, vma->vm_flags, grow);
anon_vma_interval_tree_pre_update_vma(vma);
vma->vm_end = address;
@@ -2496,7 +2496,7 @@ int expand_downwards(struct vm_area_struct *vma,
*/
spin_lock(&mm->page_table_lock);
if (vma->vm_flags & VM_LOCKED)
- mm->locked_vm += grow;
+ atomic64_add(grow, &mm->locked_vm);
vm_stat_account(mm, vma->vm_flags, grow);
anon_vma_interval_tree_pre_update_vma(vma);
vma->vm_start = address;
@@ -2839,11 +2839,11 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
/*
* unlock any mlock()ed ranges before detaching vmas
*/
- if (mm->locked_vm) {
+ if (atomic64_read(&mm->locked_vm)) {
struct vm_area_struct *tmp = vma;
while (tmp && tmp->vm_start < end) {
if (tmp->vm_flags & VM_LOCKED) {
- mm->locked_vm -= vma_pages(tmp);
+ atomic64_sub(vma_pages(tmp), &mm->locked_vm);
munlock_vma_pages_all(tmp);
}

@@ -3083,7 +3083,7 @@ static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long fla
mm->total_vm += len >> PAGE_SHIFT;
mm->data_vm += len >> PAGE_SHIFT;
if (flags & VM_LOCKED)
- mm->locked_vm += (len >> PAGE_SHIFT);
+ atomic64_add(len >> PAGE_SHIFT, &mm->locked_vm);
vma->vm_flags |= VM_SOFTDIRTY;
return 0;
}
@@ -3155,7 +3155,7 @@ void exit_mmap(struct mm_struct *mm)
mmap_write_unlock(mm);
}

- if (mm->locked_vm) {
+ if (atomic64_read(&mm->locked_vm)) {
vma = mm->mmap;
while (vma) {
if (vma->vm_flags & VM_LOCKED)
diff --git a/mm/mremap.c b/mm/mremap.c
index 138abbae4f75..451a5a77f82a 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -455,7 +455,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
}

if (vm_flags & VM_LOCKED) {
- mm->locked_vm += new_len >> PAGE_SHIFT;
+ atomic64_add(new_len >> PAGE_SHIFT, &mm->locked_vm);
*locked = true;
}
out:
@@ -520,7 +520,7 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,

if (vma->vm_flags & VM_LOCKED) {
unsigned long locked, lock_limit;
- locked = mm->locked_vm << PAGE_SHIFT;
+ locked = atomic64_read(&mm->locked_vm) << PAGE_SHIFT;
lock_limit = rlimit(RLIMIT_MEMLOCK);
locked += new_len - old_len;
if (locked > lock_limit && !capable(CAP_IPC_LOCK))
@@ -765,7 +765,7 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,

vm_stat_account(mm, vma->vm_flags, pages);
if (vma->vm_flags & VM_LOCKED) {
- mm->locked_vm += pages;
+ atomic64_add(pages, &mm->locked_vm);
locked = true;
new_addr = addr;
}
diff --git a/mm/util.c b/mm/util.c
index 8d6280c05238..473add0dc275 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -439,7 +439,7 @@ int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,

mmap_assert_write_locked(mm);

- locked_vm = mm->locked_vm;
+ locked_vm = atomic64_read(&mm->locked_vm);
if (inc) {
if (!bypass_rlim) {
limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
@@ -447,10 +447,10 @@ int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
ret = -ENOMEM;
}
if (!ret)
- mm->locked_vm = locked_vm + pages;
+ atomic64_add(pages, &mm->locked_vm);
} else {
WARN_ON_ONCE(pages > locked_vm);
- mm->locked_vm = locked_vm - pages;
+ atomic64_sub(pages, &mm->locked_vm);
}

pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
--
2.26.2
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