On Fri 16-12-16 09:22:00, 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_users' | xargs sed -i > 's/atomic_inc(&\(.*\)->mm_users);/mmget\(\1\);/' > git grep -l 'atomic_inc.*mm_users' | xargs sed -i > 's/atomic_inc(&\(.*\)\.mm_users);/mmget\(\&\1\);/' > > This is needed for a later patch that hooks into the helper, but might be > a worthwhile cleanup on its own.
Same here a clarification comment would be really nice /** * mmget: pins the address space * * Makes sure that the address space of the given mm struct doesn't go * away. This doesn't protect from freeing parts of the address space * though. * * Never use this function if the time the address space is pinned is * not bounded. */ > > Cc: Andrew Morton <[email protected]> > Cc: Michal Hocko <[email protected]> > Signed-off-by: Vegard Nossum <[email protected]> Acked-by: Michal Hocko <[email protected]> > --- > arch/arc/kernel/smp.c | 2 +- > arch/blackfin/mach-common/smp.c | 2 +- > arch/frv/mm/mmu-context.c | 2 +- > arch/metag/kernel/smp.c | 2 +- > arch/sh/kernel/smp.c | 2 +- > arch/xtensa/kernel/smp.c | 2 +- > include/linux/sched.h | 5 +++++ > kernel/fork.c | 4 ++-- > mm/swapfile.c | 10 +++++----- > virt/kvm/async_pf.c | 2 +- > 10 files changed, 19 insertions(+), 14 deletions(-) > > diff --git a/arch/arc/kernel/smp.c b/arch/arc/kernel/smp.c > index 9cbc7aba3ede..eec70cb71db1 100644 > --- a/arch/arc/kernel/smp.c > +++ b/arch/arc/kernel/smp.c > @@ -124,7 +124,7 @@ void start_kernel_secondary(void) > /* MMU, Caches, Vector Table, Interrupts etc */ > setup_processor(); > > - atomic_inc(&mm->mm_users); > + mmget(mm); > mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > diff --git a/arch/blackfin/mach-common/smp.c b/arch/blackfin/mach-common/smp.c > index bc5617ef7128..a2e6db2ce811 100644 > --- a/arch/blackfin/mach-common/smp.c > +++ b/arch/blackfin/mach-common/smp.c > @@ -307,7 +307,7 @@ void secondary_start_kernel(void) > local_irq_disable(); > > /* Attach the new idle task to the global mm. */ > - atomic_inc(&mm->mm_users); > + mmget(mm); > mmgrab(mm); > current->active_mm = mm; > > diff --git a/arch/frv/mm/mmu-context.c b/arch/frv/mm/mmu-context.c > index 81757d55a5b5..3473bde77f56 100644 > --- a/arch/frv/mm/mmu-context.c > +++ b/arch/frv/mm/mmu-context.c > @@ -188,7 +188,7 @@ int cxn_pin_by_pid(pid_t pid) > task_lock(tsk); > if (tsk->mm) { > mm = tsk->mm; > - atomic_inc(&mm->mm_users); > + mmget(mm); > ret = 0; > } > task_unlock(tsk); > diff --git a/arch/metag/kernel/smp.c b/arch/metag/kernel/smp.c > index af9cff547a19..c622293254e4 100644 > --- a/arch/metag/kernel/smp.c > +++ b/arch/metag/kernel/smp.c > @@ -344,7 +344,7 @@ 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_users); > + mmget(mm); > mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c > index ee379c699c08..edc4769b047e 100644 > --- a/arch/sh/kernel/smp.c > +++ b/arch/sh/kernel/smp.c > @@ -179,7 +179,7 @@ asmlinkage void start_secondary(void) > > enable_mmu(); > mmgrab(mm); > - atomic_inc(&mm->mm_users); > + mmget(mm); > current->active_mm = mm; > #ifdef CONFIG_MMU > enter_lazy_tlb(mm, current); > diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c > index 9bf5cea3bae4..fcea72019df7 100644 > --- a/arch/xtensa/kernel/smp.c > +++ b/arch/xtensa/kernel/smp.c > @@ -135,7 +135,7 @@ void secondary_start_kernel(void) > > /* All kernel threads share the same mm context. */ > > - atomic_inc(&mm->mm_users); > + mmget(mm); > mmgrab(mm); > current->active_mm = mm; > cpumask_set_cpu(cpu, mm_cpumask(mm)); > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 31ae1f49eebb..2ca3e15dad3b 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2899,6 +2899,11 @@ static inline void mmdrop_async(struct mm_struct *mm) > } > } > > +static inline void mmget(struct mm_struct *mm) > +{ > + atomic_inc(&mm->mm_users); > +} > + > static inline bool mmget_not_zero(struct mm_struct *mm) > { > return atomic_inc_not_zero(&mm->mm_users); > diff --git a/kernel/fork.c b/kernel/fork.c > index 997ac1d584f7..f9c32dc6ccbc 100644 > --- a/kernel/fork.c > +++ b/kernel/fork.c > @@ -989,7 +989,7 @@ struct mm_struct *get_task_mm(struct task_struct *task) > if (task->flags & PF_KTHREAD) > mm = NULL; > else > - atomic_inc(&mm->mm_users); > + mmget(mm); > } > task_unlock(task); > return mm; > @@ -1177,7 +1177,7 @@ static int copy_mm(unsigned long clone_flags, struct > task_struct *tsk) > vmacache_flush(tsk); > > if (clone_flags & CLONE_VM) { > - atomic_inc(&oldmm->mm_users); > + mmget(oldmm); > mm = oldmm; > goto good_mm; > } > diff --git a/mm/swapfile.c b/mm/swapfile.c > index f30438970cd1..cf73169ce153 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1402,7 +1402,7 @@ int try_to_unuse(unsigned int type, bool frontswap, > * that. > */ > start_mm = &init_mm; > - atomic_inc(&init_mm.mm_users); > + mmget(&init_mm); > > /* > * Keep on scanning until all entries have gone. Usually, > @@ -1451,7 +1451,7 @@ int try_to_unuse(unsigned int type, bool frontswap, > if (atomic_read(&start_mm->mm_users) == 1) { > mmput(start_mm); > start_mm = &init_mm; > - atomic_inc(&init_mm.mm_users); > + mmget(&init_mm); > } > > /* > @@ -1488,8 +1488,8 @@ int try_to_unuse(unsigned int type, bool frontswap, > struct mm_struct *prev_mm = start_mm; > struct mm_struct *mm; > > - atomic_inc(&new_start_mm->mm_users); > - atomic_inc(&prev_mm->mm_users); > + mmget(new_start_mm); > + mmget(prev_mm); > spin_lock(&mmlist_lock); > while (swap_count(*swap_map) && !retval && > (p = p->next) != &start_mm->mmlist) { > @@ -1512,7 +1512,7 @@ int try_to_unuse(unsigned int type, bool frontswap, > > if (set_start_mm && *swap_map < swcount) { > mmput(new_start_mm); > - atomic_inc(&mm->mm_users); > + mmget(mm); > new_start_mm = mm; > set_start_mm = 0; > } > diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c > index efeceb0a222d..9ec9cef2b207 100644 > --- a/virt/kvm/async_pf.c > +++ b/virt/kvm/async_pf.c > @@ -200,7 +200,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, > unsigned long hva, > work->addr = hva; > work->arch = *arch; > work->mm = current->mm; > - atomic_inc(&work->mm->mm_users); > + mmget(work->mm); > kvm_get_kvm(work->vcpu->kvm); > > /* this can't really happen otherwise gfn_to_pfn_async > -- > 2.11.0.1.gaa10c3f > -- Michal Hocko SUSE Labs
