From dd3b8353bae79395b12a178de057b183ff0122eb Mon Sep 17 00:00:00 2001 From: "Uladzislau Rezki (Sony)" Date: Mon, 23 Sep 2019 15:36:36 -0700 Subject: [PATCH] mm/vmalloc: do not keep unpurged areas in the busy tree The busy tree can be quite big, even though the area is freed or unmapped it still stays there until "purge" logic removes it. 1) Optimize and reduce the size of "busy" tree by removing a node from it right away as soon as user triggers free paths. It is possible to do so, because the allocation is done using another augmented tree. The vmalloc test driver shows the difference, for example the "fix_size_alloc_test" is ~11% better comparing with default configuration: sudo ./test_vmalloc.sh performance Summary: fix_size_alloc_test loops: 1000000 avg: 993985 usec Summary: full_fit_alloc_test loops: 1000000 avg: 973554 usec Summary: long_busy_list_alloc_test loops: 1000000 avg: 12617652 usec Summary: fix_size_alloc_test loops: 1000000 avg: 882263 usec Summary: full_fit_alloc_test loops: 1000000 avg: 973407 usec Summary: long_busy_list_alloc_test loops: 1000000 avg: 12593929 usec 2) Since the busy tree now contains allocated areas only and does not interfere with lazily free nodes, introduce the new function show_purge_info() that dumps "unpurged" areas that is propagated through "/proc/vmallocinfo". 3) Eliminate VM_LAZY_FREE flag. Link: http://lkml.kernel.org/r/20190716152656.12255-2-lpf.vector@gmail.com Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Pengfei Li Cc: Roman Gushchin Cc: Uladzislau Rezki Cc: Hillf Danton Cc: Michal Hocko Cc: Matthew Wilcox Cc: Oleksiy Avramchenko Cc: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/vmalloc.c | 52 ++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 44 insertions(+), 8 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index c1246d77cf75..d535ef125bda 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -329,7 +329,6 @@ EXPORT_SYMBOL(vmalloc_to_pfn); #define DEBUG_AUGMENT_PROPAGATE_CHECK 0 #define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0 -#define VM_LAZY_FREE 0x02 #define VM_VM_AREA 0x04 static DEFINE_SPINLOCK(vmap_area_lock); @@ -1282,7 +1281,14 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end) llist_for_each_entry_safe(va, n_va, valist, purge_list) { unsigned long nr = (va->va_end - va->va_start) >> PAGE_SHIFT; - __free_vmap_area(va); + /* + * Finally insert or merge lazily-freed area. It is + * detached and there is no need to "unlink" it from + * anything. + */ + merge_or_add_vmap_area(va, + &free_vmap_area_root, &free_vmap_area_list); + atomic_long_sub(nr, &vmap_lazy_nr); if (atomic_long_read(&vmap_lazy_nr) < resched_threshold) @@ -1324,6 +1330,10 @@ static void free_vmap_area_noflush(struct vmap_area *va) { unsigned long nr_lazy; + spin_lock(&vmap_area_lock); + unlink_va(va, &vmap_area_root); + spin_unlock(&vmap_area_lock); + nr_lazy = atomic_long_add_return((va->va_end - va->va_start) >> PAGE_SHIFT, &vmap_lazy_nr); @@ -2143,14 +2153,13 @@ struct vm_struct *remove_vm_area(const void *addr) might_sleep(); - va = find_vmap_area((unsigned long)addr); + spin_lock(&vmap_area_lock); + va = __find_vmap_area((unsigned long)addr); if (va && va->flags & VM_VM_AREA) { struct vm_struct *vm = va->vm; - spin_lock(&vmap_area_lock); va->vm = NULL; va->flags &= ~VM_VM_AREA; - va->flags |= VM_LAZY_FREE; spin_unlock(&vmap_area_lock); kasan_free_shadow(vm); @@ -2158,6 +2167,8 @@ struct vm_struct *remove_vm_area(const void *addr) return vm; } + + spin_unlock(&vmap_area_lock); return NULL; } @@ -3450,6 +3461,22 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v) } } +static void show_purge_info(struct seq_file *m) +{ + struct llist_node *head; + struct vmap_area *va; + + head = READ_ONCE(vmap_purge_list.first); + if (head == NULL) + return; + + llist_for_each_entry(va, head, purge_list) { + seq_printf(m, "0x%pK-0x%pK %7ld unpurged vm_area\n", + (void *)va->va_start, (void *)va->va_end, + va->va_end - va->va_start); + } +} + static int s_show(struct seq_file *m, void *p) { struct vmap_area *va; @@ -3462,10 +3489,9 @@ static int s_show(struct seq_file *m, void *p) * behalf of vmap area is being tear down or vm_map_ram allocation. */ if (!(va->flags & VM_VM_AREA)) { - seq_printf(m, "0x%pK-0x%pK %7ld %s\n", + seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n", (void *)va->va_start, (void *)va->va_end, - va->va_end - va->va_start, - va->flags & VM_LAZY_FREE ? "unpurged vm_area" : "vm_map_ram"); + va->va_end - va->va_start); return 0; } @@ -3504,6 +3530,16 @@ static int s_show(struct seq_file *m, void *p) show_numa_info(m, v); seq_putc(m, '\n'); + + /* + * As a final step, dump "unpurged" areas. Note, + * that entire "/proc/vmallocinfo" output will not + * be address sorted, because the purge list is not + * sorted. + */ + if (list_is_last(&va->list, &vmap_area_list)) + show_purge_info(m); + return 0; }