Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760376AbcLPJqf (ORCPT ); Fri, 16 Dec 2016 04:46:35 -0500 Received: from mail-wj0-f196.google.com ([209.85.210.196]:36633 "EHLO mail-wj0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753214AbcLPJq1 (ORCPT ); Fri, 16 Dec 2016 04:46:27 -0500 Date: Fri, 16 Dec 2016 10:14:17 +0100 From: Michal Hocko To: Vegard Nossum Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Rik van Riel , Matthew Wilcox , Peter Zijlstra , Andrew Morton , Al Viro , Ingo Molnar , Linus Torvalds Subject: Re: [PATCH 1/4] mm: add new mmgrab() helper Message-ID: <20161216091417.GB13940@dhcp22.suse.cz> References: <20161216082202.21044-1-vegard.nossum@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161216082202.21044-1-vegard.nossum@oracle.com> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 23084 Lines: 646 On Fri 16-12-16 09:21:59, Vegard Nossum wrote: > Apart from adding the helper function itself, the rest of the kernel is > converted mechanically using: > > git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)->mm_count);/mmgrab\(\1\);/' > git grep -l 'atomic_inc.*mm_count' | xargs sed -i 's/atomic_inc(&\(.*\)\.mm_count);/mmgrab\(\&\1\);/' > > This is needed for a later patch that hooks into the helper, but might be > a worthwhile cleanup on its own. > > Cc: Andrew Morton > Cc: Michal Hocko > Signed-off-by: Vegard Nossum Yes this make sense to me. I usually do not like wrappers around simple atomic operations but the api will be more symmetric (and cscope will work nicer as a bonus). While you are there a comment explaining where mmgrab should be used would be nice /** * mmgrab: pins the mm_struct * * Make sure that the mm struct will not get freed even after the owner * task exits. This doesn't guarantee that the associated address space * will still exist later on and mmget_not_zero has to be used before * accessing it. * * This is a preferred way to to pin the mm struct for longer/unbound * time. */ or something along those lines. Anyway Acked-by: Michal Hocko > --- > arch/alpha/kernel/smp.c | 2 +- > arch/arc/kernel/smp.c | 2 +- > arch/arm/kernel/smp.c | 2 +- > arch/arm64/kernel/smp.c | 2 +- > arch/blackfin/mach-common/smp.c | 2 +- > arch/hexagon/kernel/smp.c | 2 +- > arch/ia64/kernel/setup.c | 2 +- > arch/m32r/kernel/setup.c | 2 +- > arch/metag/kernel/smp.c | 2 +- > arch/mips/kernel/traps.c | 2 +- > arch/mn10300/kernel/smp.c | 2 +- > arch/parisc/kernel/smp.c | 2 +- > arch/powerpc/kernel/smp.c | 2 +- > arch/s390/kernel/processor.c | 2 +- > arch/score/kernel/traps.c | 2 +- > arch/sh/kernel/smp.c | 2 +- > arch/sparc/kernel/leon_smp.c | 2 +- > arch/sparc/kernel/smp_64.c | 2 +- > arch/sparc/kernel/sun4d_smp.c | 2 +- > arch/sparc/kernel/sun4m_smp.c | 2 +- > arch/sparc/kernel/traps_32.c | 2 +- > arch/sparc/kernel/traps_64.c | 2 +- > arch/tile/kernel/smpboot.c | 2 +- > arch/x86/kernel/cpu/common.c | 4 ++-- > arch/xtensa/kernel/smp.c | 2 +- > drivers/gpu/drm/amd/amdkfd/kfd_process.c | 2 +- > drivers/gpu/drm/i915/i915_gem_userptr.c | 2 +- > drivers/infiniband/hw/hfi1/file_ops.c | 2 +- > fs/proc/base.c | 4 ++-- > fs/userfaultfd.c | 2 +- > include/linux/sched.h | 5 +++++ > kernel/exit.c | 2 +- > kernel/futex.c | 2 +- > kernel/sched/core.c | 4 ++-- > mm/khugepaged.c | 2 +- > mm/ksm.c | 2 +- > mm/mmu_context.c | 2 +- > mm/mmu_notifier.c | 2 +- > mm/oom_kill.c | 4 ++-- > virt/kvm/kvm_main.c | 2 +- > 40 files changed, 48 insertions(+), 43 deletions(-) > > diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c > index 46bf263c3153..acb4b146a607 100644 > --- a/arch/alpha/kernel/smp.c > +++ b/arch/alpha/kernel/smp.c > @@ -144,7 +144,7 @@ smp_callin(void) > alpha_mv.smp_callin(); > > /* All kernel threads share the same mm context. */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > /* inform the notifiers about the new cpu */ > diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c > index 88674d972c9d..9cbc7aba3ede 100644 > --- a/arch/arc/kernel/smp.c > +++ b/arch/arc/kernel/smp.c > @@ -125,7 +125,7 @@ void start_kernel_secondary(void) > setup_processor(); > > atomic_inc(&mm->mm_users); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > > diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c > index 7dd14e8395e6..c6514ce0fcbc 100644 > --- a/arch/arm/kernel/smp.c > +++ b/arch/arm/kernel/smp.c > @@ -371,7 +371,7 @@ asmlinkage void secondary_start_kernel(void) > * reference and switch to it. > */ > cpu = smp_processor_id(); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index 8507703dabe4..61969ea29654 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -214,7 +214,7 @@ asmlinkage void secondary_start_kernel(void) > * All kernel threads share the same mm context; grab a > * reference and switch to it. > */ > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > current->active_mm = mm; > > set_my_cpu_offset(per_cpu_offset(smp_processor_id())); > diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c > index 23c4ef5f8bdc..bc5617ef7128 100644 > --- a/arch/blackfin/mach-common/smp.c > +++ b/arch/blackfin/mach-common/smp.c > @@ -308,7 +308,7 @@ void secondary_start_kernel(void) > > /* Attach the new idle task to the global mm. */ > atomic_inc(&mm->mm_users); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > current->active_mm = mm; > > preempt_disable(); > diff --git a/arch/hexagon/kernel/smp.c b/arch/hexagon/kernel/smp.c > index 983bae7d2665..c02a6455839e 100644 > --- a/arch/hexagon/kernel/smp.c > +++ b/arch/hexagon/kernel/smp.c > @@ -162,7 +162,7 @@ void start_secondary(void) > ); > > /* Set the memory struct */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > cpu = smp_processor_id(); > diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c > index 7ec7acc844c2..ecbff47b01f1 100644 > --- a/arch/ia64/kernel/setup.c > +++ b/arch/ia64/kernel/setup.c > @@ -992,7 +992,7 @@ cpu_init (void) > */ > ia64_setreg(_IA64_REG_CR_DCR, ( IA64_DCR_DP | IA64_DCR_DK | IA64_DCR_DX | IA64_DCR_DR > | IA64_DCR_DA | IA64_DCR_DD | IA64_DCR_LC)); > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > BUG_ON(current->mm); > > diff --git a/arch/m32r/kernel/setup.c b/arch/m32r/kernel/setup.c > index 136c69f1fb8a..b18bc0bd6544 100644 > --- a/arch/m32r/kernel/setup.c > +++ b/arch/m32r/kernel/setup.c > @@ -403,7 +403,7 @@ void __init cpu_init (void) > printk(KERN_INFO "Initializing CPU#%d\n", cpu_id); > > /* Set up and load the per-CPU TSS and LDT */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > if (current->mm) > BUG(); > diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c > index bad13232de51..af9cff547a19 100644 > --- a/arch/metag/kernel/smp.c > +++ b/arch/metag/kernel/smp.c > @@ -345,7 +345,7 @@ asmlinkage void secondary_start_kernel(void) > * reference and switch to it. > */ > atomic_inc(&mm->mm_users); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > enter_lazy_tlb(mm, current); > diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c > index 3905003dfe2b..e50b0e0ca44c 100644 > --- a/arch/mips/kernel/traps.c > +++ b/arch/mips/kernel/traps.c > @@ -2177,7 +2177,7 @@ void per_cpu_trap_init(bool is_boot_cpu) > if (!cpu_data[cpu].asid_cache) > cpu_data[cpu].asid_cache = asid_first_version(cpu); > > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > BUG_ON(current->mm); > enter_lazy_tlb(&init_mm, current); > diff --git a/arch/mn10300/kernel/smp.c b/arch/mn10300/kernel/smp.c > index 426173c4b0b9..e65b5cc2fa67 100644 > --- a/arch/mn10300/kernel/smp.c > +++ b/arch/mn10300/kernel/smp.c > @@ -589,7 +589,7 @@ static void __init smp_cpu_init(void) > } > printk(KERN_INFO "Initializing CPU#%d\n", cpu_id); > > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > BUG_ON(current->mm); > > diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c > index 75dab2871346..67b452b41ff6 100644 > --- a/arch/parisc/kernel/smp.c > +++ b/arch/parisc/kernel/smp.c > @@ -279,7 +279,7 @@ smp_cpu_init(int cpunum) > set_cpu_online(cpunum, true); > > /* Initialise the idle task for this CPU */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > BUG_ON(current->mm); > enter_lazy_tlb(&init_mm, current); > diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c > index 9c6f3fd58059..42b82364c782 100644 > --- a/arch/powerpc/kernel/smp.c > +++ b/arch/powerpc/kernel/smp.c > @@ -707,7 +707,7 @@ void start_secondary(void *unused) > unsigned int cpu = smp_processor_id(); > int i, base; > > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > smp_store_cpu_info(cpu); > diff --git a/arch/s390/kernel/processor.c b/arch/s390/kernel/processor.c > index 81d0808085e6..ec9bc100895c 100644 > --- a/arch/s390/kernel/processor.c > +++ b/arch/s390/kernel/processor.c > @@ -73,7 +73,7 @@ void cpu_init(void) > get_cpu_id(id); > if (machine_has_cpu_mhz) > update_cpu_mhz(NULL); > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > BUG_ON(current->mm); > enter_lazy_tlb(&init_mm, current); > diff --git a/arch/score/kernel/traps.c b/arch/score/kernel/traps.c > index 5cea1e750cec..6f6e5a39d147 100644 > --- a/arch/score/kernel/traps.c > +++ b/arch/score/kernel/traps.c > @@ -336,7 +336,7 @@ void __init trap_init(void) > set_except_vector(18, handle_dbe); > flush_icache_range(DEBUG_VECTOR_BASE_ADDR, IRQ_VECTOR_BASE_ADDR); > > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > cpu_cache_init(); > } > diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c > index 38e7860845db..ee379c699c08 100644 > --- a/arch/sh/kernel/smp.c > +++ b/arch/sh/kernel/smp.c > @@ -178,7 +178,7 @@ asmlinkage void start_secondary(void) > struct mm_struct *mm = &init_mm; > > enable_mmu(); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > atomic_inc(&mm->mm_users); > current->active_mm = mm; > #ifdef CONFIG_MMU > diff --git a/arch/sparc/kernel/leon_smp.c b/arch/sparc/kernel/leon_smp.c > index 71e16f2241c2..b99d33797e1d 100644 > --- a/arch/sparc/kernel/leon_smp.c > +++ b/arch/sparc/kernel/leon_smp.c > @@ -93,7 +93,7 @@ void leon_cpu_pre_online(void *arg) > : "memory" /* paranoid */); > > /* Attach to the address space of init_task. */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > while (!cpumask_test_cpu(cpuid, &smp_commenced_mask)) > diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c > index 8182f7caf5b1..c1d2bed22961 100644 > --- a/arch/sparc/kernel/smp_64.c > +++ b/arch/sparc/kernel/smp_64.c > @@ -122,7 +122,7 @@ void smp_callin(void) > current_thread_info()->new_child = 0; > > /* Attach to the address space of init_task. */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > /* inform the notifiers about the new cpu */ > diff --git a/arch/sparc/kernel/sun4d_smp.c b/arch/sparc/kernel/sun4d_smp.c > index 9d98e5002a09..7b55c50eabe5 100644 > --- a/arch/sparc/kernel/sun4d_smp.c > +++ b/arch/sparc/kernel/sun4d_smp.c > @@ -93,7 +93,7 @@ void sun4d_cpu_pre_online(void *arg) > show_leds(cpuid); > > /* Attach to the address space of init_task. */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > local_ops->cache_all(); > diff --git a/arch/sparc/kernel/sun4m_smp.c b/arch/sparc/kernel/sun4m_smp.c > index 278c40abce82..633c4cf6fdb0 100644 > --- a/arch/sparc/kernel/sun4m_smp.c > +++ b/arch/sparc/kernel/sun4m_smp.c > @@ -59,7 +59,7 @@ void sun4m_cpu_pre_online(void *arg) > : "memory" /* paranoid */); > > /* Attach to the address space of init_task. */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > while (!cpumask_test_cpu(cpuid, &smp_commenced_mask)) > diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c > index 4f21df7d4f13..ecddac5a4c96 100644 > --- a/arch/sparc/kernel/traps_32.c > +++ b/arch/sparc/kernel/traps_32.c > @@ -448,7 +448,7 @@ void trap_init(void) > thread_info_offsets_are_bolixed_pete(); > > /* Attach to the address space of init_task. */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > > /* NOTE: Other cpus have this done as they are started > diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c > index 4094a51b1970..0dbbe40012ef 100644 > --- a/arch/sparc/kernel/traps_64.c > +++ b/arch/sparc/kernel/traps_64.c > @@ -2764,6 +2764,6 @@ void __init trap_init(void) > /* Attach to the address space of init_task. On SMP we > * do this in smp.c:smp_callin for other cpus. > */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > } > diff --git a/arch/tile/kernel/smpboot.c b/arch/tile/kernel/smpboot.c > index 6c0abaacec33..53ce940a5016 100644 > --- a/arch/tile/kernel/smpboot.c > +++ b/arch/tile/kernel/smpboot.c > @@ -160,7 +160,7 @@ static void start_secondary(void) > __this_cpu_write(current_asid, min_asid); > > /* Set up this thread as another owner of the init_mm */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > current->active_mm = &init_mm; > if (current->mm) > BUG(); > diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c > index cc9e980c68ec..b580da4582e1 100644 > --- a/arch/x86/kernel/cpu/common.c > +++ b/arch/x86/kernel/cpu/common.c > @@ -1555,7 +1555,7 @@ void cpu_init(void) > for (i = 0; i <= IO_BITMAP_LONGS; i++) > t->io_bitmap[i] = ~0UL; > > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > me->active_mm = &init_mm; > BUG_ON(me->mm); > enter_lazy_tlb(&init_mm, me); > @@ -1606,7 +1606,7 @@ void cpu_init(void) > /* > * Set up and load the per-CPU TSS and LDT > */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > curr->active_mm = &init_mm; > BUG_ON(curr->mm); > enter_lazy_tlb(&init_mm, curr); > diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c > index fc4ad21a5ed4..9bf5cea3bae4 100644 > --- a/arch/xtensa/kernel/smp.c > +++ b/arch/xtensa/kernel/smp.c > @@ -136,7 +136,7 @@ void secondary_start_kernel(void) > /* All kernel threads share the same mm context. */ > > atomic_inc(&mm->mm_users); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > enter_lazy_tlb(mm, current); > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c > index ef7c8de7060e..ca5f2aa7232d 100644 > --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c > @@ -262,7 +262,7 @@ static void kfd_process_notifier_release(struct mmu_notifier *mn, > * and because the mmu_notifier_unregister function also drop > * mm_count we need to take an extra count here. > */ > - atomic_inc(&p->mm->mm_count); > + mmgrab(p->mm); > mmu_notifier_unregister_no_release(&p->mmu_notifier, p->mm); > mmu_notifier_call_srcu(&p->rcu, &kfd_process_destroy_delayed); > } > diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c > index c6f780f5abc9..f21ca404af79 100644 > --- a/drivers/gpu/drm/i915/i915_gem_userptr.c > +++ b/drivers/gpu/drm/i915/i915_gem_userptr.c > @@ -341,7 +341,7 @@ i915_gem_userptr_init__mm_struct(struct drm_i915_gem_object *obj) > mm->i915 = to_i915(obj->base.dev); > > mm->mm = current->mm; > - atomic_inc(¤t->mm->mm_count); > + mmgrab(current->mm); > > mm->mn = NULL; > > diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c > index bd786b7bd30b..2e1a6643a910 100644 > --- a/drivers/infiniband/hw/hfi1/file_ops.c > +++ b/drivers/infiniband/hw/hfi1/file_ops.c > @@ -185,7 +185,7 @@ static int hfi1_file_open(struct inode *inode, struct file *fp) > if (fd) { > fd->rec_cpu_num = -1; /* no cpu affinity by default */ > fd->mm = current->mm; > - atomic_inc(&fd->mm->mm_count); > + mmgrab(fd->mm); > fp->private_data = fd; > } else { > fp->private_data = NULL; > diff --git a/fs/proc/base.c b/fs/proc/base.c > index ca651ac00660..0b8ccacae8b3 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -795,7 +795,7 @@ struct mm_struct *proc_mem_open(struct inode *inode, unsigned int mode) > > if (!IS_ERR_OR_NULL(mm)) { > /* ensure this mm_struct can't be freed */ > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > /* but do not pin its memory */ > mmput(mm); > } > @@ -1093,7 +1093,7 @@ static int __set_oom_adj(struct file *file, int oom_adj, bool legacy) > if (p) { > if (atomic_read(&p->mm->mm_users) > 1) { > mm = p->mm; > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > } > task_unlock(p); > } > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index 85959d8324df..ffa9c7cbc5fa 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -1304,7 +1304,7 @@ static struct file *userfaultfd_file_create(int flags) > ctx->released = false; > ctx->mm = current->mm; > /* prevent the mm struct to be freed */ > - atomic_inc(&ctx->mm->mm_count); > + mmgrab(ctx->mm); > > file = anon_inode_getfile("[userfaultfd]", &userfaultfd_fops, ctx, > O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS)); > diff --git a/include/linux/sched.h b/include/linux/sched.h > index e9c009dc3a4a..31ae1f49eebb 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2872,6 +2872,11 @@ static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig) > */ > extern struct mm_struct * mm_alloc(void); > > +static inline void mmgrab(struct mm_struct *mm) > +{ > + atomic_inc(&mm->mm_count); > +} > + > /* mmdrop drops the mm and the page tables */ > extern void __mmdrop(struct mm_struct *); > static inline void mmdrop(struct mm_struct *mm) > diff --git a/kernel/exit.c b/kernel/exit.c > index 3076f3089919..b12753840050 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -500,7 +500,7 @@ static void exit_mm(struct task_struct *tsk) > __set_task_state(tsk, TASK_RUNNING); > down_read(&mm->mmap_sem); > } > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > BUG_ON(mm != tsk->active_mm); > /* more a memory barrier than a real lock */ > task_lock(tsk); > diff --git a/kernel/futex.c b/kernel/futex.c > index 2c4be467fecd..cbe6056c17c1 100644 > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -338,7 +338,7 @@ static inline bool should_fail_futex(bool fshared) > > static inline void futex_get_mm(union futex_key *key) > { > - atomic_inc(&key->private.mm->mm_count); > + mmgrab(key->private.mm); > /* > * Ensure futex_get_mm() implies a full barrier such that > * get_futex_key() implies a full barrier. This is relied upon > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 154fd689fe02..ee1fb0070544 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -2877,7 +2877,7 @@ context_switch(struct rq *rq, struct task_struct *prev, > > if (!mm) { > next->active_mm = oldmm; > - atomic_inc(&oldmm->mm_count); > + mmgrab(oldmm); > enter_lazy_tlb(oldmm, next); > } else > switch_mm_irqs_off(oldmm, mm, next); > @@ -7667,7 +7667,7 @@ void __init sched_init(void) > /* > * The boot idle thread does lazy MMU switching as well: > */ > - atomic_inc(&init_mm.mm_count); > + mmgrab(&init_mm); > enter_lazy_tlb(&init_mm, current); > > /* > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 87e1a7ca3846..1343271a18f1 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -420,7 +420,7 @@ int __khugepaged_enter(struct mm_struct *mm) > list_add_tail(&mm_slot->mm_node, &khugepaged_scan.mm_head); > spin_unlock(&khugepaged_mm_lock); > > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > if (wakeup) > wake_up_interruptible(&khugepaged_wait); > > diff --git a/mm/ksm.c b/mm/ksm.c > index 9ae6011a41f8..5a49aad9d87b 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -1813,7 +1813,7 @@ int __ksm_enter(struct mm_struct *mm) > spin_unlock(&ksm_mmlist_lock); > > set_bit(MMF_VM_MERGEABLE, &mm->flags); > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > > if (needs_wakeup) > wake_up_interruptible(&ksm_thread_wait); > diff --git a/mm/mmu_context.c b/mm/mmu_context.c > index 6f4d27c5bb32..daf67bb02b4a 100644 > --- a/mm/mmu_context.c > +++ b/mm/mmu_context.c > @@ -25,7 +25,7 @@ void use_mm(struct mm_struct *mm) > task_lock(tsk); > active_mm = tsk->active_mm; > if (active_mm != mm) { > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > tsk->active_mm = mm; > } > tsk->mm = mm; > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index f4259e496f83..32bc9f2ff7eb 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -275,7 +275,7 @@ static int do_mmu_notifier_register(struct mmu_notifier *mn, > mm->mmu_notifier_mm = mmu_notifier_mm; > mmu_notifier_mm = NULL; > } > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > > /* > * Serialize the update against mmu_notifier_unregister. A > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index ec9f11d4f094..ead093c6f2a6 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -660,7 +660,7 @@ static void mark_oom_victim(struct task_struct *tsk) > > /* oom_mm is bound to the signal struct life time. */ > if (!cmpxchg(&tsk->signal->oom_mm, NULL, mm)) > - atomic_inc(&tsk->signal->oom_mm->mm_count); > + mmgrab(tsk->signal->oom_mm); > > /* > * Make sure that the task is woken up from uninterruptible sleep > @@ -877,7 +877,7 @@ static void oom_kill_process(struct oom_control *oc, const char *message) > > /* Get a reference to safely compare mm after task_unlock(victim) */ > mm = victim->mm; > - atomic_inc(&mm->mm_count); > + mmgrab(mm); > /* > * We should send SIGKILL before setting TIF_MEMDIE in order to prevent > * the OOM victim from depleting the memory reserves from the user > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 7f9ee2929cfe..43914b981691 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -613,7 +613,7 @@ static struct kvm *kvm_create_vm(unsigned long type) > return ERR_PTR(-ENOMEM); > > spin_lock_init(&kvm->mmu_lock); > - atomic_inc(¤t->mm->mm_count); > + mmgrab(current->mm); > kvm->mm = current->mm; > kvm_eventfd_init(kvm); > mutex_init(&kvm->lock); > -- > 2.11.0.1.gaa10c3f > -- Michal Hocko SUSE Labs