diff --git a/include/linux/fs.h b/include/linux/fs.h index 4019e6fa3b95..8cf258fc9162 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -515,6 +515,11 @@ static inline void i_mmap_unlock_write(struct address_space *mapping) up_write(&mapping->i_mmap_rwsem); } +static inline int i_mmap_trylock_read(struct address_space *mapping) +{ + return down_read_trylock(&mapping->i_mmap_rwsem); +} + static inline void i_mmap_lock_read(struct address_space *mapping) { down_read(&mapping->i_mmap_rwsem); diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 7dee138fbf0f..0a4d49ca8ccf 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -134,6 +134,11 @@ static inline void anon_vma_lock_read(struct anon_vma *anon_vma) down_read(&anon_vma->root->rwsem); } +static inline int anon_vma_trylock_read(struct anon_vma *anon_vma) +{ + return down_read_trylock(&anon_vma->root->rwsem); +} + static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) { up_read(&anon_vma->root->rwsem); @@ -261,17 +266,14 @@ void try_to_munlock(struct page *); void remove_migration_ptes(struct page *old, struct page *new, bool locked); -/* - * Called by memory-failure.c to kill processes. - */ -struct anon_vma *page_lock_anon_vma_read(struct page *page); -void page_unlock_anon_vma_read(struct anon_vma *anon_vma); int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); /* * rmap_walk_control: To control rmap traversing for specific needs * * arg: passed to rmap_one() and invalid_vma() + * try_lock: bail out if the rmap lock is contended + * contended: indicate the rmap traversal bailed out due to lock contention * rmap_one: executed on each vma where page is mapped * done: for checking traversing termination condition * anon_lock: for getting anon_lock by optimized way rather than default @@ -279,6 +281,8 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); */ struct rmap_walk_control { void *arg; + bool try_lock; + bool contended; /* * Return false if page table scanning in rmap_walk should be stopped. * Otherwise, return true. @@ -286,13 +290,21 @@ struct rmap_walk_control { bool (*rmap_one)(struct page *page, struct vm_area_struct *vma, unsigned long addr, void *arg); int (*done)(struct page *page); - struct anon_vma *(*anon_lock)(struct page *page); + struct anon_vma *(*anon_lock)(struct page *page, + struct rmap_walk_control *rwc); bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); }; void rmap_walk(struct page *page, struct rmap_walk_control *rwc); void rmap_walk_locked(struct page *page, struct rmap_walk_control *rwc); +/* + * Called by memory-failure.c to kill processes. + */ +struct anon_vma *page_lock_anon_vma_read(struct page *page, + struct rmap_walk_control *rwc); +void page_unlock_anon_vma_read(struct anon_vma *anon_vma); + #else /* !CONFIG_MMU */ #define anon_vma_init() do {} while (0) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index c24716571a93..d10c9c3118a8 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1481,7 +1481,7 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, pmd_t pmd) */ get_page(page); spin_unlock(vmf->ptl); - anon_vma = page_lock_anon_vma_read(page); + anon_vma = page_lock_anon_vma_read(page, NULL); /* Confirm the PMD did not change while page_table_lock was released */ spin_lock(vmf->ptl); diff --git a/mm/ksm.c b/mm/ksm.c index e2464c04ede2..2695ddbeb47e 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2626,7 +2626,13 @@ void rmap_walk_ksm(struct page *page, struct rmap_walk_control *rwc) struct vm_area_struct *vma; cond_resched(); - anon_vma_lock_read(anon_vma); + if (!anon_vma_trylock_read(anon_vma)) { + if (rwc->try_lock) { + rwc->contended = true; + return; + } + anon_vma_lock_read(anon_vma); + } anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root, 0, ULONG_MAX) { unsigned long addr; diff --git a/mm/memory-failure.c b/mm/memory-failure.c index aef267c6a724..4bd73d6dc18a 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -477,7 +477,7 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill, struct anon_vma *av; pgoff_t pgoff; - av = page_lock_anon_vma_read(page); + av = page_lock_anon_vma_read(page, NULL); if (av == NULL) /* Not actually mapped anymore */ return; diff --git a/mm/page_idle.c b/mm/page_idle.c index 144fb4ed961d..b5613232e881 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -92,10 +92,10 @@ static bool page_idle_clear_pte_refs_one(struct page *page, static void page_idle_clear_pte_refs(struct page *page) { /* - * Since rwc.arg is unused, rwc is effectively immutable, so we - * can make it static const to save some cycles and stack. + * Since rwc.try_lock is unused, rwc is effectively immutable, so we + * can make it static to save some cycles and stack. */ - static const struct rmap_walk_control rwc = { + static struct rmap_walk_control rwc = { .rmap_one = page_idle_clear_pte_refs_one, .anon_lock = page_lock_anon_vma_read, }; diff --git a/mm/rmap.c b/mm/rmap.c index d48141f90360..033b04704b59 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -518,9 +518,11 @@ struct anon_vma *page_get_anon_vma(struct page *page) * * Its a little more complex as it tries to keep the fast path to a single * atomic op -- the trylock. If we fail the trylock, we fall back to getting a - * reference like with page_get_anon_vma() and then block on the mutex. + * reference like with page_get_anon_vma() and then block on the mutex + * on !rwc->try_lock case. */ -struct anon_vma *page_lock_anon_vma_read(struct page *page) +struct anon_vma *page_lock_anon_vma_read(struct page *page, + struct rmap_walk_control *rwc) { struct anon_vma *anon_vma = NULL; struct anon_vma *root_anon_vma; @@ -553,6 +555,13 @@ struct anon_vma *page_lock_anon_vma_read(struct page *page) anon_vma = NULL; goto out; } + + if (rwc && rwc->try_lock) { + anon_vma = NULL; + rwc->contended = true; + goto out; + } + /* trylock failed, we got to sleep */ if (!atomic_inc_not_zero(&anon_vma->refcount)) { anon_vma = NULL; @@ -850,8 +859,10 @@ static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) * @memcg: target memory cgroup * @vm_flags: collect encountered vma->vm_flags who actually referenced the page * - * Quick test_and_clear_referenced for all mappings to a page, - * returns the number of ptes which referenced the page. + * Quick test_and_clear_referenced for all mappings of a page, + * + * Return: The number of mappings which referenced the page. Return -1 if + * the function bailed out due to rmap lock contention. */ int page_referenced(struct page *page, int is_locked, @@ -867,6 +878,7 @@ int page_referenced(struct page *page, .rmap_one = page_referenced_one, .arg = (void *)&pra, .anon_lock = page_lock_anon_vma_read, + .try_lock = true, }; *vm_flags = 0; @@ -897,7 +909,7 @@ int page_referenced(struct page *page, if (we_locked) unlock_page(page); - return pra.referenced; + return rwc.contended ? -1 : pra.referenced; } static bool page_mkclean_one(struct page *page, struct vm_area_struct *vma, @@ -1898,7 +1910,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page, struct anon_vma *anon_vma; if (rwc->anon_lock) - return rwc->anon_lock(page); + return rwc->anon_lock(page, rwc); /* * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() @@ -1910,7 +1922,17 @@ static struct anon_vma *rmap_walk_anon_lock(struct page *page, if (!anon_vma) return NULL; + if (anon_vma_trylock_read(anon_vma)) + goto out; + + if (rwc->try_lock) { + anon_vma = NULL; + rwc->contended = true; + goto out; + } + anon_vma_lock_read(anon_vma); +out: return anon_vma; } @@ -2009,9 +2031,18 @@ static void rmap_walk_file(struct page *page, struct rmap_walk_control *rwc, if (!got_lock) return; } else { + if (i_mmap_trylock_read(mapping)) + goto lookup; + + if (rwc->try_lock) { + rwc->contended = true; + return; + } + i_mmap_lock_read(mapping); } } +lookup: vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff_start, pgoff_end) { unsigned long address = vma_address(page, vma); diff --git a/mm/vmscan.c b/mm/vmscan.c index 701595410992..ea87d599199e 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1045,6 +1045,10 @@ static enum page_references page_check_references(struct page *page, if (vm_flags & VM_LOCKED) return PAGEREF_RECLAIM; + /* rmap lock contention: rotate */ + if (referenced_ptes == -1) + return PAGEREF_KEEP; + if (referenced_ptes) { /* * All mapped pages start out with page table @@ -2119,8 +2123,9 @@ static void shrink_active_list(unsigned long nr_to_scan, if (bypass) goto skip_page_referenced; trace_android_vh_page_trylock_set(page); + /* Referenced or rmap lock contention: rotate */ if (page_referenced(page, 0, sc->target_mem_cgroup, - &vm_flags)) { + &vm_flags) != 0) { /* * Identify referenced, file-backed active pages and * give them one more trip around the active list. So