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Message-ID: <4140911c-8193-010b-e8fc-c8b24ffdf423@c-s.fr>
Date: Wed, 3 Apr 2019 06:46:07 +0200
From: Christophe Leroy <christophe.leroy@....fr>
To: Daniel Jordan <daniel.m.jordan@...cle.com>,
akpm@...ux-foundation.org
Cc: Davidlohr Bueso <dave@...olabs.net>, kvm@...r.kernel.org,
Alan Tull <atull@...nel.org>,
Alexey Kardashevskiy <aik@...abs.ru>,
linux-fpga@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm-ppc@...r.kernel.org, linux-mm@...ck.org,
Alex Williamson <alex.williamson@...hat.com>,
Moritz Fischer <mdf@...nel.org>,
Christoph Lameter <cl@...ux.com>,
linuxppc-dev@...ts.ozlabs.org, Wu Hao <hao.wu@...el.com>
Subject: Re: [PATCH 1/6] mm: change locked_vm's type from unsigned long to
atomic64_t
Le 02/04/2019 à 22:41, Daniel Jordan a écrit :
> Taking and dropping mmap_sem to modify a single counter, locked_vm, is
> overkill when the counter could be synchronized separately.
>
> Make mmap_sem a little less coarse by changing locked_vm to an atomic,
> the 64-bit variety to avoid issues with overflow on 32-bit systems.
Can you elaborate on the above ? Previously it was 'unsigned long', what
were the issues ? If there was such issues, shouldn't there be a first
patch moving it from unsigned long to u64 before this atomic64_t change
? Or at least it should be clearly explain here what the issues are and
how switching to a 64 bit counter fixes them.
Christophe
>
> Signed-off-by: Daniel Jordan <daniel.m.jordan@...cle.com>
> Cc: Alan Tull <atull@...nel.org>
> Cc: Alexey Kardashevskiy <aik@...abs.ru>
> Cc: Alex Williamson <alex.williamson@...hat.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Cc: Christoph Lameter <cl@...ux.com>
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Moritz Fischer <mdf@...nel.org>
> Cc: Paul Mackerras <paulus@...abs.org>
> Cc: Wu Hao <hao.wu@...el.com>
> Cc: <linux-mm@...ck.org>
> Cc: <kvm@...r.kernel.org>
> Cc: <kvm-ppc@...r.kernel.org>
> Cc: <linuxppc-dev@...ts.ozlabs.org>
> Cc: <linux-fpga@...r.kernel.org>
> Cc: <linux-kernel@...r.kernel.org>
> ---
> arch/powerpc/kvm/book3s_64_vio.c | 14 ++++++++------
> arch/powerpc/mm/mmu_context_iommu.c | 15 ++++++++-------
> drivers/fpga/dfl-afu-dma-region.c | 18 ++++++++++--------
> drivers/vfio/vfio_iommu_spapr_tce.c | 17 +++++++++--------
> drivers/vfio/vfio_iommu_type1.c | 10 ++++++----
> fs/proc/task_mmu.c | 2 +-
> include/linux/mm_types.h | 2 +-
> kernel/fork.c | 2 +-
> mm/debug.c | 5 +++--
> mm/mlock.c | 4 ++--
> mm/mmap.c | 18 +++++++++---------
> mm/mremap.c | 6 +++---
> 12 files changed, 61 insertions(+), 52 deletions(-)
>
> diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
> index f02b04973710..e7fdb6d10eeb 100644
> --- a/arch/powerpc/kvm/book3s_64_vio.c
> +++ b/arch/powerpc/kvm/book3s_64_vio.c
> @@ -59,32 +59,34 @@ static unsigned long kvmppc_stt_pages(unsigned long tce_pages)
> static long kvmppc_account_memlimit(unsigned long stt_pages, bool inc)
> {
> long ret = 0;
> + s64 locked_vm;
>
> if (!current || !current->mm)
> return ret; /* process exited */
>
> down_write(¤t->mm->mmap_sem);
>
> + locked_vm = atomic64_read(¤t->mm->locked_vm);
> if (inc) {
> unsigned long locked, lock_limit;
>
> - locked = current->mm->locked_vm + stt_pages;
> + locked = locked_vm + stt_pages;
> lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> if (locked > lock_limit && !capable(CAP_IPC_LOCK))
> ret = -ENOMEM;
> else
> - current->mm->locked_vm += stt_pages;
> + atomic64_add(stt_pages, ¤t->mm->locked_vm);
> } else {
> - if (WARN_ON_ONCE(stt_pages > current->mm->locked_vm))
> - stt_pages = current->mm->locked_vm;
> + if (WARN_ON_ONCE(stt_pages > locked_vm))
> + stt_pages = locked_vm;
>
> - current->mm->locked_vm -= stt_pages;
> + atomic64_sub(stt_pages, ¤t->mm->locked_vm);
> }
>
> pr_debug("[%d] RLIMIT_MEMLOCK KVM %c%ld %ld/%ld%s\n", current->pid,
> inc ? '+' : '-',
> stt_pages << PAGE_SHIFT,
> - current->mm->locked_vm << PAGE_SHIFT,
> + atomic64_read(¤t->mm->locked_vm) << PAGE_SHIFT,
> rlimit(RLIMIT_MEMLOCK),
> ret ? " - exceeded" : "");
>
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> index e7a9c4f6bfca..8038ac24a312 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -55,30 +55,31 @@ static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
> unsigned long npages, bool incr)
> {
> long ret = 0, locked, lock_limit;
> + s64 locked_vm;
>
> if (!npages)
> return 0;
>
> down_write(&mm->mmap_sem);
> -
> + locked_vm = atomic64_read(&mm->locked_vm);
> if (incr) {
> - locked = mm->locked_vm + npages;
> + locked = locked_vm + npages;
> lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> if (locked > lock_limit && !capable(CAP_IPC_LOCK))
> ret = -ENOMEM;
> else
> - mm->locked_vm += npages;
> + atomic64_add(npages, &mm->locked_vm);
> } else {
> - if (WARN_ON_ONCE(npages > mm->locked_vm))
> - npages = mm->locked_vm;
> - mm->locked_vm -= npages;
> + if (WARN_ON_ONCE(npages > locked_vm))
> + npages = locked_vm;
> + atomic64_sub(npages, &mm->locked_vm);
> }
>
> pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
> current ? current->pid : 0,
> incr ? '+' : '-',
> npages << PAGE_SHIFT,
> - mm->locked_vm << PAGE_SHIFT,
> + atomic64_read(&mm->locked_vm) << PAGE_SHIFT,
> rlimit(RLIMIT_MEMLOCK));
> up_write(&mm->mmap_sem);
>
> diff --git a/drivers/fpga/dfl-afu-dma-region.c b/drivers/fpga/dfl-afu-dma-region.c
> index e18a786fc943..08132fd9b6b7 100644
> --- a/drivers/fpga/dfl-afu-dma-region.c
> +++ b/drivers/fpga/dfl-afu-dma-region.c
> @@ -45,6 +45,7 @@ void afu_dma_region_init(struct dfl_feature_platform_data *pdata)
> static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
> {
> unsigned long locked, lock_limit;
> + s64 locked_vm;
> int ret = 0;
>
> /* the task is exiting. */
> @@ -53,24 +54,25 @@ static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
>
> down_write(¤t->mm->mmap_sem);
>
> + locked_vm = atomic64_read(¤t->mm->locked_vm);
> if (incr) {
> - locked = current->mm->locked_vm + npages;
> + locked = locked_vm + npages;
> lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
>
> if (locked > lock_limit && !capable(CAP_IPC_LOCK))
> ret = -ENOMEM;
> else
> - current->mm->locked_vm += npages;
> + atomic64_add(npages, ¤t->mm->locked_vm);
> } else {
> - if (WARN_ON_ONCE(npages > current->mm->locked_vm))
> - npages = current->mm->locked_vm;
> - current->mm->locked_vm -= npages;
> + if (WARN_ON_ONCE(npages > locked_vm))
> + npages = locked_vm;
> + atomic64_sub(npages, ¤t->mm->locked_vm);
> }
>
> - dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %ld/%ld%s\n", current->pid,
> + dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %lld/%lu%s\n", current->pid,
> incr ? '+' : '-', npages << PAGE_SHIFT,
> - current->mm->locked_vm << PAGE_SHIFT, rlimit(RLIMIT_MEMLOCK),
> - ret ? "- exceeded" : "");
> + (s64)atomic64_read(¤t->mm->locked_vm) << PAGE_SHIFT,
> + rlimit(RLIMIT_MEMLOCK), ret ? "- exceeded" : "");
>
> up_write(¤t->mm->mmap_sem);
>
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 8dbb270998f4..e7d787e5d839 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -36,7 +36,8 @@ static void tce_iommu_detach_group(void *iommu_data,
>
> static long try_increment_locked_vm(struct mm_struct *mm, long npages)
> {
> - long ret = 0, locked, lock_limit;
> + long ret = 0, lock_limit;
> + s64 locked;
>
> if (WARN_ON_ONCE(!mm))
> return -EPERM;
> @@ -45,16 +46,16 @@ static long try_increment_locked_vm(struct mm_struct *mm, long npages)
> return 0;
>
> down_write(&mm->mmap_sem);
> - locked = mm->locked_vm + npages;
> + locked = atomic64_read(&mm->locked_vm) + npages;
> lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
> if (locked > lock_limit && !capable(CAP_IPC_LOCK))
> ret = -ENOMEM;
> else
> - mm->locked_vm += npages;
> + atomic64_add(npages, &mm->locked_vm);
>
> pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
> npages << PAGE_SHIFT,
> - mm->locked_vm << PAGE_SHIFT,
> + atomic64_read(&mm->locked_vm) << PAGE_SHIFT,
> rlimit(RLIMIT_MEMLOCK),
> ret ? " - exceeded" : "");
>
> @@ -69,12 +70,12 @@ static void decrement_locked_vm(struct mm_struct *mm, long npages)
> return;
>
> down_write(&mm->mmap_sem);
> - if (WARN_ON_ONCE(npages > mm->locked_vm))
> - npages = mm->locked_vm;
> - mm->locked_vm -= npages;
> + if (WARN_ON_ONCE(npages > atomic64_read(&mm->locked_vm)))
> + npages = atomic64_read(&mm->locked_vm);
> + atomic64_sub(npages, &mm->locked_vm);
> pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
> npages << PAGE_SHIFT,
> - mm->locked_vm << PAGE_SHIFT,
> + atomic64_read(&mm->locked_vm) << PAGE_SHIFT,
> rlimit(RLIMIT_MEMLOCK));
> up_write(&mm->mmap_sem);
> }
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 73652e21efec..5b2878697286 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -270,18 +270,19 @@ static int vfio_lock_acct(struct vfio_dma *dma, long npage, bool async)
> if (!ret) {
> if (npage > 0) {
> if (!dma->lock_cap) {
> + s64 locked_vm = atomic64_read(&mm->locked_vm);
> unsigned long limit;
>
> limit = task_rlimit(dma->task,
> RLIMIT_MEMLOCK) >> PAGE_SHIFT;
>
> - if (mm->locked_vm + npage > limit)
> + if (locked_vm + npage > limit)
> ret = -ENOMEM;
> }
> }
>
> if (!ret)
> - mm->locked_vm += npage;
> + atomic64_add(npage, &mm->locked_vm);
>
> up_write(&mm->mmap_sem);
> }
> @@ -401,6 +402,7 @@ static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
> long ret, pinned = 0, lock_acct = 0;
> bool rsvd;
> dma_addr_t iova = vaddr - dma->vaddr + dma->iova;
> + atomic64_t *locked_vm = ¤t->mm->locked_vm;
>
> /* This code path is only user initiated */
> if (!current->mm)
> @@ -418,7 +420,7 @@ 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(locked_vm) + 1 > limit) {
> put_pfn(*pfn_base, dma->prot);
> pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__,
> limit << PAGE_SHIFT);
> @@ -445,7 +447,7 @@ 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(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/proc/task_mmu.c b/fs/proc/task_mmu.c
> index 92a91e7816d8..61da4b24d0e0 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 7eade9132f02..5059b99a0827 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -410,7 +410,7 @@ 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 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 */
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 9dcd18aa210b..56be8cdc7b4a 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -979,7 +979,7 @@ 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 eee9c221280c..b9cd71927d3c 100644
> --- a/mm/debug.c
> +++ b/mm/debug.c
> @@ -136,7 +136,7 @@ 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"
> @@ -167,7 +167,8 @@ 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 080f3b36415b..e492a155c51a 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -562,7 +562,7 @@ 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_sem held in write mode.
> @@ -687,7 +687,7 @@ static __must_check int do_mlock(unsigned long start, size_t len, vm_flags_t fla
> if (down_write_killable(¤t->mm->mmap_sem))
> return -EINTR;
>
> - locked += current->mm->locked_vm;
> + locked += atomic64_read(¤t->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 41eb48d9b527..03576c1d530c 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -1339,7 +1339,7 @@ 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))
> @@ -1825,7 +1825,7 @@ 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)
> @@ -2301,7 +2301,7 @@ 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))
> @@ -2395,7 +2395,7 @@ 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;
> @@ -2475,7 +2475,7 @@ 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;
> @@ -2796,11 +2796,11 @@ 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);
> }
>
> @@ -3043,7 +3043,7 @@ 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;
> }
> @@ -3115,7 +3115,7 @@ void exit_mmap(struct mm_struct *mm)
> up_write(&mm->mmap_sem);
> }
>
> - 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 e3edef6b7a12..9a4046bb2875 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -422,7 +422,7 @@ 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;
> }
>
> @@ -473,7 +473,7 @@ 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))
> @@ -679,7 +679,7 @@ 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;
> }
>
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