On Thu 14-09-17 13:19:38, Andrew Morton wrote:
> From: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Subject: include/linux/sched/mm.h: uninline mmdrop_async(), etc
>
> mmdrop_async() is only used in fork.c. Move that and its support
> functions into fork.c, uninline it all.
Is this really an improvement? Why do we want to discourage more code
paths to use mmdrop_async? It sounds like a useful api and it has been
removed only because it lost its own user in oom code. Now that we have
a user I would just keep it where it was before.
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
>
> include/linux/sched/mm.h | 24 -
> kernel/fork.c | 455 +++++++++++++++++++------------------
> 2 files changed, 241 insertions(+), 238 deletions(-)
>
> diff -puN include/linux/sched/mm.h~include-linux-sched-mmh-uninline-mmdrop_async-etc include/linux/sched/mm.h
> --- a/include/linux/sched/mm.h~include-linux-sched-mmh-uninline-mmdrop_async-etc
> +++ a/include/linux/sched/mm.h
> @@ -10,7 +10,7 @@
> /*
> * Routines for handling mm_structs
> */
> -extern struct mm_struct * mm_alloc(void);
> +extern struct mm_struct *mm_alloc(void);
>
> /**
> * mmgrab() - Pin a &struct mm_struct.
> @@ -34,27 +34,7 @@ static inline void mmgrab(struct mm_stru
> 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)
> -{
> - if (unlikely(atomic_dec_and_test(&mm->mm_count)))
> - __mmdrop(mm);
> -}
> -
> -static inline void mmdrop_async_fn(struct work_struct *work)
> -{
> - struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
> - __mmdrop(mm);
> -}
> -
> -static inline void mmdrop_async(struct mm_struct *mm)
> -{
> - if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
> - INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
> - schedule_work(&mm->async_put_work);
> - }
> -}
> +extern void mmdrop(struct mm_struct *mm);
>
> /**
> * mmget() - Pin the address space associated with a &struct mm_struct.
> diff -puN kernel/fork.c~include-linux-sched-mmh-uninline-mmdrop_async-etc kernel/fork.c
> --- a/kernel/fork.c~include-linux-sched-mmh-uninline-mmdrop_async-etc
> +++ a/kernel/fork.c
> @@ -77,6 +77,7 @@
> #include <linux/blkdev.h>
> #include <linux/fs_struct.h>
> #include <linux/magic.h>
> +#include <linux/sched/mm.h>
> #include <linux/perf_event.h>
> #include <linux/posix-timers.h>
> #include <linux/user-return-notifier.h>
> @@ -386,6 +387,244 @@ void free_task(struct task_struct *tsk)
> }
> EXPORT_SYMBOL(free_task);
>
> +#ifdef CONFIG_MMU
> +static __latent_entropy int dup_mmap(struct mm_struct *mm,
> + struct mm_struct *oldmm)
> +{
> + struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
> + struct rb_node **rb_link, *rb_parent;
> + int retval;
> + unsigned long charge;
> + LIST_HEAD(uf);
> +
> + uprobe_start_dup_mmap();
> + if (down_write_killable(&oldmm->mmap_sem)) {
> + retval = -EINTR;
> + goto fail_uprobe_end;
> + }
> + flush_cache_dup_mm(oldmm);
> + uprobe_dup_mmap(oldmm, mm);
> + /*
> + * Not linked in yet - no deadlock potential:
> + */
> + down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
> +
> + /* No ordering required: file already has been exposed. */
> + RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
> +
> + mm->total_vm = oldmm->total_vm;
> + mm->data_vm = oldmm->data_vm;
> + mm->exec_vm = oldmm->exec_vm;
> + mm->stack_vm = oldmm->stack_vm;
> +
> + rb_link = &mm->mm_rb.rb_node;
> + rb_parent = NULL;
> + pprev = &mm->mmap;
> + retval = ksm_fork(mm, oldmm);
> + if (retval)
> + goto out;
> + retval = khugepaged_fork(mm, oldmm);
> + if (retval)
> + goto out;
> +
> + prev = NULL;
> + for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
> + struct file *file;
> +
> + if (mpnt->vm_flags & VM_DONTCOPY) {
> + vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
> + continue;
> + }
> + charge = 0;
> + if (mpnt->vm_flags & VM_ACCOUNT) {
> + unsigned long len = vma_pages(mpnt);
> +
> + if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
> + goto fail_nomem;
> + charge = len;
> + }
> + tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
> + if (!tmp)
> + goto fail_nomem;
> + *tmp = *mpnt;
> + INIT_LIST_HEAD(&tmp->anon_vma_chain);
> + retval = vma_dup_policy(mpnt, tmp);
> + if (retval)
> + goto fail_nomem_policy;
> + tmp->vm_mm = mm;
> + retval = dup_userfaultfd(tmp, &uf);
> + if (retval)
> + goto fail_nomem_anon_vma_fork;
> + if (tmp->vm_flags & VM_WIPEONFORK) {
> + /* VM_WIPEONFORK gets a clean slate in the child. */
> + tmp->anon_vma = NULL;
> + if (anon_vma_prepare(tmp))
> + goto fail_nomem_anon_vma_fork;
> + } else if (anon_vma_fork(tmp, mpnt))
> + goto fail_nomem_anon_vma_fork;
> + tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
> + tmp->vm_next = tmp->vm_prev = NULL;
> + file = tmp->vm_file;
> + if (file) {
> + struct inode *inode = file_inode(file);
> + struct address_space *mapping = file->f_mapping;
> +
> + get_file(file);
> + if (tmp->vm_flags & VM_DENYWRITE)
> + atomic_dec(&inode->i_writecount);
> + i_mmap_lock_write(mapping);
> + if (tmp->vm_flags & VM_SHARED)
> + atomic_inc(&mapping->i_mmap_writable);
> + flush_dcache_mmap_lock(mapping);
> + /* insert tmp into the share list, just after mpnt */
> + vma_interval_tree_insert_after(tmp, mpnt,
> + &mapping->i_mmap);
> + flush_dcache_mmap_unlock(mapping);
> + i_mmap_unlock_write(mapping);
> + }
> +
> + /*
> + * Clear hugetlb-related page reserves for children. This only
> + * affects MAP_PRIVATE mappings. Faults generated by the child
> + * are not guaranteed to succeed, even if read-only
> + */
> + if (is_vm_hugetlb_page(tmp))
> + reset_vma_resv_huge_pages(tmp);
> +
> + /*
> + * Link in the new vma and copy the page table entries.
> + */
> + *pprev = tmp;
> + pprev = &tmp->vm_next;
> + tmp->vm_prev = prev;
> + prev = tmp;
> +
> + __vma_link_rb(mm, tmp, rb_link, rb_parent);
> + rb_link = &tmp->vm_rb.rb_right;
> + rb_parent = &tmp->vm_rb;
> +
> + mm->map_count++;
> + if (!(tmp->vm_flags & VM_WIPEONFORK))
> + retval = copy_page_range(mm, oldmm, mpnt);
> +
> + if (tmp->vm_ops && tmp->vm_ops->open)
> + tmp->vm_ops->open(tmp);
> +
> + if (retval)
> + goto out;
> + }
> + /* a new mm has just been created */
> + arch_dup_mmap(oldmm, mm);
> + retval = 0;
> +out:
> + up_write(&mm->mmap_sem);
> + flush_tlb_mm(oldmm);
> + up_write(&oldmm->mmap_sem);
> + dup_userfaultfd_complete(&uf);
> +fail_uprobe_end:
> + uprobe_end_dup_mmap();
> + return retval;
> +fail_nomem_anon_vma_fork:
> + mpol_put(vma_policy(tmp));
> +fail_nomem_policy:
> + kmem_cache_free(vm_area_cachep, tmp);
> +fail_nomem:
> + retval = -ENOMEM;
> + vm_unacct_memory(charge);
> + goto out;
> +}
> +
> +static inline int mm_alloc_pgd(struct mm_struct *mm)
> +{
> + mm->pgd = pgd_alloc(mm);
> + if (unlikely(!mm->pgd))
> + return -ENOMEM;
> + return 0;
> +}
> +
> +static inline void mm_free_pgd(struct mm_struct *mm)
> +{
> + pgd_free(mm, mm->pgd);
> +}
> +#else
> +static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
> +{
> + down_write(&oldmm->mmap_sem);
> + RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
> + up_write(&oldmm->mmap_sem);
> + return 0;
> +}
> +#define mm_alloc_pgd(mm) (0)
> +#define mm_free_pgd(mm)
> +#endif /* CONFIG_MMU */
> +
> +static void check_mm(struct mm_struct *mm)
> +{
> + int i;
> +
> + for (i = 0; i < NR_MM_COUNTERS; i++) {
> + long x = atomic_long_read(&mm->rss_stat.count[i]);
> +
> + if (unlikely(x))
> + printk(KERN_ALERT "BUG: Bad rss-counter state "
> + "mm:%p idx:%d val:%ld\n", mm, i, x);
> + }
> +
> + if (atomic_long_read(&mm->nr_ptes))
> + pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
> + atomic_long_read(&mm->nr_ptes));
> + if (mm_nr_pmds(mm))
> + pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
> + mm_nr_pmds(mm));
> +
> +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
> + VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
> +#endif
> +}
> +
> +#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
> +#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
> +
> +/*
> + * Called when the last reference to the mm
> + * is dropped: either by a lazy thread or by
> + * mmput. Free the page directory and the mm.
> + */
> +static void __mmdrop(struct mm_struct *mm)
> +{
> + BUG_ON(mm == &init_mm);
> + mm_free_pgd(mm);
> + destroy_context(mm);
> + hmm_mm_destroy(mm);
> + mmu_notifier_mm_destroy(mm);
> + check_mm(mm);
> + put_user_ns(mm->user_ns);
> + free_mm(mm);
> +}
> +
> +void mmdrop(struct mm_struct *mm)
> +{
> + if (unlikely(atomic_dec_and_test(&mm->mm_count)))
> + __mmdrop(mm);
> +}
> +EXPORT_SYMBOL_GPL(mmdrop);
> +
> +static void mmdrop_async_fn(struct work_struct *work)
> +{
> + struct mm_struct *mm;
> +
> + mm = container_of(work, struct mm_struct, async_put_work);
> + __mmdrop(mm);
> +}
> +
> +static void mmdrop_async(struct mm_struct *mm)
> +{
> + if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
> + INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
> + schedule_work(&mm->async_put_work);
> + }
> +}
> +
> static inline void free_signal_struct(struct signal_struct *sig)
> {
> taskstats_tgid_free(sig);
> @@ -590,182 +829,8 @@ free_tsk:
> return NULL;
> }
>
> -#ifdef CONFIG_MMU
> -static __latent_entropy int dup_mmap(struct mm_struct *mm,
> - struct mm_struct *oldmm)
> -{
> - struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
> - struct rb_node **rb_link, *rb_parent;
> - int retval;
> - unsigned long charge;
> - LIST_HEAD(uf);
> -
> - uprobe_start_dup_mmap();
> - if (down_write_killable(&oldmm->mmap_sem)) {
> - retval = -EINTR;
> - goto fail_uprobe_end;
> - }
> - flush_cache_dup_mm(oldmm);
> - uprobe_dup_mmap(oldmm, mm);
> - /*
> - * Not linked in yet - no deadlock potential:
> - */
> - down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
> -
> - /* No ordering required: file already has been exposed. */
> - RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
> -
> - mm->total_vm = oldmm->total_vm;
> - mm->data_vm = oldmm->data_vm;
> - mm->exec_vm = oldmm->exec_vm;
> - mm->stack_vm = oldmm->stack_vm;
> -
> - rb_link = &mm->mm_rb.rb_node;
> - rb_parent = NULL;
> - pprev = &mm->mmap;
> - retval = ksm_fork(mm, oldmm);
> - if (retval)
> - goto out;
> - retval = khugepaged_fork(mm, oldmm);
> - if (retval)
> - goto out;
> -
> - prev = NULL;
> - for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
> - struct file *file;
> -
> - if (mpnt->vm_flags & VM_DONTCOPY) {
> - vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
> - continue;
> - }
> - charge = 0;
> - if (mpnt->vm_flags & VM_ACCOUNT) {
> - unsigned long len = vma_pages(mpnt);
> -
> - if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
> - goto fail_nomem;
> - charge = len;
> - }
> - tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
> - if (!tmp)
> - goto fail_nomem;
> - *tmp = *mpnt;
> - INIT_LIST_HEAD(&tmp->anon_vma_chain);
> - retval = vma_dup_policy(mpnt, tmp);
> - if (retval)
> - goto fail_nomem_policy;
> - tmp->vm_mm = mm;
> - retval = dup_userfaultfd(tmp, &uf);
> - if (retval)
> - goto fail_nomem_anon_vma_fork;
> - if (tmp->vm_flags & VM_WIPEONFORK) {
> - /* VM_WIPEONFORK gets a clean slate in the child. */
> - tmp->anon_vma = NULL;
> - if (anon_vma_prepare(tmp))
> - goto fail_nomem_anon_vma_fork;
> - } else if (anon_vma_fork(tmp, mpnt))
> - goto fail_nomem_anon_vma_fork;
> - tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
> - tmp->vm_next = tmp->vm_prev = NULL;
> - file = tmp->vm_file;
> - if (file) {
> - struct inode *inode = file_inode(file);
> - struct address_space *mapping = file->f_mapping;
> -
> - get_file(file);
> - if (tmp->vm_flags & VM_DENYWRITE)
> - atomic_dec(&inode->i_writecount);
> - i_mmap_lock_write(mapping);
> - if (tmp->vm_flags & VM_SHARED)
> - atomic_inc(&mapping->i_mmap_writable);
> - flush_dcache_mmap_lock(mapping);
> - /* insert tmp into the share list, just after mpnt */
> - vma_interval_tree_insert_after(tmp, mpnt,
> - &mapping->i_mmap);
> - flush_dcache_mmap_unlock(mapping);
> - i_mmap_unlock_write(mapping);
> - }
> -
> - /*
> - * Clear hugetlb-related page reserves for children. This only
> - * affects MAP_PRIVATE mappings. Faults generated by the child
> - * are not guaranteed to succeed, even if read-only
> - */
> - if (is_vm_hugetlb_page(tmp))
> - reset_vma_resv_huge_pages(tmp);
> -
> - /*
> - * Link in the new vma and copy the page table entries.
> - */
> - *pprev = tmp;
> - pprev = &tmp->vm_next;
> - tmp->vm_prev = prev;
> - prev = tmp;
> -
> - __vma_link_rb(mm, tmp, rb_link, rb_parent);
> - rb_link = &tmp->vm_rb.rb_right;
> - rb_parent = &tmp->vm_rb;
> -
> - mm->map_count++;
> - if (!(tmp->vm_flags & VM_WIPEONFORK))
> - retval = copy_page_range(mm, oldmm, mpnt);
> -
> - if (tmp->vm_ops && tmp->vm_ops->open)
> - tmp->vm_ops->open(tmp);
> -
> - if (retval)
> - goto out;
> - }
> - /* a new mm has just been created */
> - arch_dup_mmap(oldmm, mm);
> - retval = 0;
> -out:
> - up_write(&mm->mmap_sem);
> - flush_tlb_mm(oldmm);
> - up_write(&oldmm->mmap_sem);
> - dup_userfaultfd_complete(&uf);
> -fail_uprobe_end:
> - uprobe_end_dup_mmap();
> - return retval;
> -fail_nomem_anon_vma_fork:
> - mpol_put(vma_policy(tmp));
> -fail_nomem_policy:
> - kmem_cache_free(vm_area_cachep, tmp);
> -fail_nomem:
> - retval = -ENOMEM;
> - vm_unacct_memory(charge);
> - goto out;
> -}
> -
> -static inline int mm_alloc_pgd(struct mm_struct *mm)
> -{
> - mm->pgd = pgd_alloc(mm);
> - if (unlikely(!mm->pgd))
> - return -ENOMEM;
> - return 0;
> -}
> -
> -static inline void mm_free_pgd(struct mm_struct *mm)
> -{
> - pgd_free(mm, mm->pgd);
> -}
> -#else
> -static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
> -{
> - down_write(&oldmm->mmap_sem);
> - RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
> - up_write(&oldmm->mmap_sem);
> - return 0;
> -}
> -#define mm_alloc_pgd(mm) (0)
> -#define mm_free_pgd(mm)
> -#endif /* CONFIG_MMU */
> -
> __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
>
> -#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
> -#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
> -
> static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
>
> static int __init coredump_filter_setup(char *s)
> @@ -856,30 +921,6 @@ fail_nopgd:
> return NULL;
> }
>
> -static void check_mm(struct mm_struct *mm)
> -{
> - int i;
> -
> - for (i = 0; i < NR_MM_COUNTERS; i++) {
> - long x = atomic_long_read(&mm->rss_stat.count[i]);
> -
> - if (unlikely(x))
> - printk(KERN_ALERT "BUG: Bad rss-counter state "
> - "mm:%p idx:%d val:%ld\n", mm, i, x);
> - }
> -
> - if (atomic_long_read(&mm->nr_ptes))
> - pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
> - atomic_long_read(&mm->nr_ptes));
> - if (mm_nr_pmds(mm))
> - pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
> - mm_nr_pmds(mm));
> -
> -#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
> - VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
> -#endif
> -}
> -
> /*
> * Allocate and initialize an mm_struct.
> */
> @@ -895,24 +936,6 @@ struct mm_struct *mm_alloc(void)
> return mm_init(mm, current, current_user_ns());
> }
>
> -/*
> - * Called when the last reference to the mm
> - * is dropped: either by a lazy thread or by
> - * mmput. Free the page directory and the mm.
> - */
> -void __mmdrop(struct mm_struct *mm)
> -{
> - BUG_ON(mm == &init_mm);
> - mm_free_pgd(mm);
> - destroy_context(mm);
> - hmm_mm_destroy(mm);
> - mmu_notifier_mm_destroy(mm);
> - check_mm(mm);
> - put_user_ns(mm->user_ns);
> - free_mm(mm);
> -}
> -EXPORT_SYMBOL_GPL(__mmdrop);
> -
> static inline void __mmput(struct mm_struct *mm)
> {
> VM_BUG_ON(atomic_read(&mm->mm_users));
> _
>
> Patches currently in -mm which might be from akpm@xxxxxxxxxxxxxxxxxxxx are
>
> i-need-old-gcc.patch
> drivers-media-cec-cec-adapc-fix-build-with-gcc-444.patch
> mm-oom_reaper-skip-mm-structs-with-mmu-notifiers-checkpatch-fixes.patch
> arm-arch-arm-include-asm-pageh-needs-personalityh.patch
> ocfs2-old-mle-put-and-release-after-the-function-dlm_add_migration_mle-called-fix.patch
> mm.patch
> include-linux-sched-mmh-uninline-mmdrop_async-etc.patch
> kernel-reboot-add-devm_register_reboot_notifier-fix.patch
> linux-next-git-rejects.patch
> kernel-forkc-export-kernel_thread-to-modules.patch
> slab-leaks3-default-y.patch
>
> --
> To unsubscribe from this list: send the line "unsubscribe mm-commits" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
