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![Wang YanQing](/assets/img/avatar_default.png)
Commit d2c5e30c9a
("[PATCH] zoned vm counters: conversion of nr_bounce to per zone counter")
convert statistic of nr_bounce to per zone and one global value in vm_stat,
but it call inc_|dec_zone_page_state on different pages, then different
zones, and cause us to get unexpected value of NR_BOUNCE.
Below is the result on my machine:
Mar 2 09:26:08 udknight kernel: [144766.778265] Mem-Info:
Mar 2 09:26:08 udknight kernel: [144766.778266] DMA per-cpu:
Mar 2 09:26:08 udknight kernel: [144766.778268] CPU 0: hi: 0, btch: 1 usd: 0
Mar 2 09:26:08 udknight kernel: [144766.778269] CPU 1: hi: 0, btch: 1 usd: 0
Mar 2 09:26:08 udknight kernel: [144766.778270] Normal per-cpu:
Mar 2 09:26:08 udknight kernel: [144766.778271] CPU 0: hi: 186, btch: 31 usd: 0
Mar 2 09:26:08 udknight kernel: [144766.778273] CPU 1: hi: 186, btch: 31 usd: 0
Mar 2 09:26:08 udknight kernel: [144766.778274] HighMem per-cpu:
Mar 2 09:26:08 udknight kernel: [144766.778275] CPU 0: hi: 186, btch: 31 usd: 0
Mar 2 09:26:08 udknight kernel: [144766.778276] CPU 1: hi: 186, btch: 31 usd: 0
Mar 2 09:26:08 udknight kernel: [144766.778279] active_anon:46926 inactive_anon:287406 isolated_anon:0
Mar 2 09:26:08 udknight kernel: [144766.778279] active_file:105085 inactive_file:139432 isolated_file:0
Mar 2 09:26:08 udknight kernel: [144766.778279] unevictable:653 dirty:0 writeback:0 unstable:0
Mar 2 09:26:08 udknight kernel: [144766.778279] free:178957 slab_reclaimable:6419 slab_unreclaimable:9966
Mar 2 09:26:08 udknight kernel: [144766.778279] mapped:4426 shmem:305277 pagetables:784 bounce:0
Mar 2 09:26:08 udknight kernel: [144766.778279] free_cma:0
Mar 2 09:26:08 udknight kernel: [144766.778286] DMA free:3324kB min:68kB low:84kB high:100kB active_anon:0kB inactive_anon:0kB active_file:0kB inactive_file:0kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15976kB managed:15900kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? yes
Mar 2 09:26:08 udknight kernel: [144766.778287] lowmem_reserve[]: 0 822 3754 3754
Mar 2 09:26:08 udknight kernel: [144766.778293] Normal free:26828kB min:3632kB low:4540kB high:5448kB active_anon:4872kB inactive_anon:68kB active_file:1796kB inactive_file:1796kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:892920kB managed:842560kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:4144kB slab_reclaimable:25676kB slab_unreclaimable:39864kB kernel_stack:1944kB pagetables:3136kB unstable:0kB bounce:0kB free_cma:0kB writeback_tmp:0kB pages_scanned:2412612 all_unreclaimable? yes
Mar 2 09:26:08 udknight kernel: [144766.778294] lowmem_reserve[]: 0 0 23451 23451
Mar 2 09:26:08 udknight kernel: [144766.778299] HighMem free:685676kB min:512kB low:3748kB high:6984kB active_anon:182832kB inactive_anon:1149556kB active_file:418544kB inactive_file:555932kB unevictable:2612kB isolated(anon):0kB isolated(file):0kB present:3001732kB managed:3001732kB mlocked:0kB dirty:0kB writeback:0kB mapped:17704kB shmem:1216964kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:75771152kB free_cma:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
Mar 2 09:26:08 udknight kernel: [144766.778300] lowmem_reserve[]: 0 0 0 0
You can see bounce:75771152kB for HighMem, but bounce:0 for lowmem and global.
This patch fix it.
Signed-off-by: Wang YanQing <udknight@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
290 lines
6.5 KiB
C
290 lines
6.5 KiB
C
/* bounce buffer handling for block devices
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*
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* - Split from highmem.c
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/mm.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/gfp.h>
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#include <linux/bio.h>
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#include <linux/pagemap.h>
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#include <linux/mempool.h>
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#include <linux/blkdev.h>
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#include <linux/init.h>
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#include <linux/hash.h>
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#include <linux/highmem.h>
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#include <linux/bootmem.h>
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#include <linux/printk.h>
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#include <asm/tlbflush.h>
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#include <trace/events/block.h>
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#define POOL_SIZE 64
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#define ISA_POOL_SIZE 16
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static mempool_t *page_pool, *isa_page_pool;
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#if defined(CONFIG_HIGHMEM) || defined(CONFIG_NEED_BOUNCE_POOL)
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static __init int init_emergency_pool(void)
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{
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#if defined(CONFIG_HIGHMEM) && !defined(CONFIG_MEMORY_HOTPLUG)
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if (max_pfn <= max_low_pfn)
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return 0;
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#endif
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page_pool = mempool_create_page_pool(POOL_SIZE, 0);
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BUG_ON(!page_pool);
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pr_info("pool size: %d pages\n", POOL_SIZE);
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return 0;
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}
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__initcall(init_emergency_pool);
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#endif
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#ifdef CONFIG_HIGHMEM
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/*
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* highmem version, map in to vec
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*/
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static void bounce_copy_vec(struct bio_vec *to, unsigned char *vfrom)
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{
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unsigned long flags;
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unsigned char *vto;
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local_irq_save(flags);
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vto = kmap_atomic(to->bv_page);
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memcpy(vto + to->bv_offset, vfrom, to->bv_len);
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kunmap_atomic(vto);
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local_irq_restore(flags);
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}
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#else /* CONFIG_HIGHMEM */
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#define bounce_copy_vec(to, vfrom) \
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memcpy(page_address((to)->bv_page) + (to)->bv_offset, vfrom, (to)->bv_len)
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#endif /* CONFIG_HIGHMEM */
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/*
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* allocate pages in the DMA region for the ISA pool
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*/
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static void *mempool_alloc_pages_isa(gfp_t gfp_mask, void *data)
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{
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return mempool_alloc_pages(gfp_mask | GFP_DMA, data);
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}
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/*
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* gets called "every" time someone init's a queue with BLK_BOUNCE_ISA
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* as the max address, so check if the pool has already been created.
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*/
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int init_emergency_isa_pool(void)
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{
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if (isa_page_pool)
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return 0;
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isa_page_pool = mempool_create(ISA_POOL_SIZE, mempool_alloc_pages_isa,
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mempool_free_pages, (void *) 0);
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BUG_ON(!isa_page_pool);
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pr_info("isa pool size: %d pages\n", ISA_POOL_SIZE);
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return 0;
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}
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/*
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* Simple bounce buffer support for highmem pages. Depending on the
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* queue gfp mask set, *to may or may not be a highmem page. kmap it
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* always, it will do the Right Thing
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*/
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static void copy_to_high_bio_irq(struct bio *to, struct bio *from)
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{
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unsigned char *vfrom;
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struct bio_vec tovec, *fromvec = from->bi_io_vec;
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struct bvec_iter iter;
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bio_for_each_segment(tovec, to, iter) {
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if (tovec.bv_page != fromvec->bv_page) {
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/*
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* fromvec->bv_offset and fromvec->bv_len might have
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* been modified by the block layer, so use the original
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* copy, bounce_copy_vec already uses tovec->bv_len
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*/
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vfrom = page_address(fromvec->bv_page) +
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tovec.bv_offset;
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bounce_copy_vec(&tovec, vfrom);
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flush_dcache_page(tovec.bv_page);
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}
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fromvec++;
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}
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}
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static void bounce_end_io(struct bio *bio, mempool_t *pool, int err)
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{
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struct bio *bio_orig = bio->bi_private;
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struct bio_vec *bvec, *org_vec;
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int i;
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if (test_bit(BIO_EOPNOTSUPP, &bio->bi_flags))
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set_bit(BIO_EOPNOTSUPP, &bio_orig->bi_flags);
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/*
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* free up bounce indirect pages used
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*/
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bio_for_each_segment_all(bvec, bio, i) {
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org_vec = bio_orig->bi_io_vec + i;
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if (bvec->bv_page == org_vec->bv_page)
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continue;
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dec_zone_page_state(bvec->bv_page, NR_BOUNCE);
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mempool_free(bvec->bv_page, pool);
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}
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bio_endio(bio_orig, err);
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bio_put(bio);
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}
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static void bounce_end_io_write(struct bio *bio, int err)
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{
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bounce_end_io(bio, page_pool, err);
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}
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static void bounce_end_io_write_isa(struct bio *bio, int err)
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{
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bounce_end_io(bio, isa_page_pool, err);
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}
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static void __bounce_end_io_read(struct bio *bio, mempool_t *pool, int err)
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{
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struct bio *bio_orig = bio->bi_private;
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if (test_bit(BIO_UPTODATE, &bio->bi_flags))
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copy_to_high_bio_irq(bio_orig, bio);
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bounce_end_io(bio, pool, err);
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}
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static void bounce_end_io_read(struct bio *bio, int err)
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{
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__bounce_end_io_read(bio, page_pool, err);
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}
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static void bounce_end_io_read_isa(struct bio *bio, int err)
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{
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__bounce_end_io_read(bio, isa_page_pool, err);
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}
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#ifdef CONFIG_NEED_BOUNCE_POOL
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static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
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{
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if (bio_data_dir(bio) != WRITE)
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return 0;
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if (!bdi_cap_stable_pages_required(&q->backing_dev_info))
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return 0;
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return test_bit(BIO_SNAP_STABLE, &bio->bi_flags);
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}
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#else
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static int must_snapshot_stable_pages(struct request_queue *q, struct bio *bio)
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{
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return 0;
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}
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#endif /* CONFIG_NEED_BOUNCE_POOL */
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static void __blk_queue_bounce(struct request_queue *q, struct bio **bio_orig,
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mempool_t *pool, int force)
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{
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struct bio *bio;
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int rw = bio_data_dir(*bio_orig);
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struct bio_vec *to, from;
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struct bvec_iter iter;
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unsigned i;
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if (force)
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goto bounce;
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bio_for_each_segment(from, *bio_orig, iter)
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if (page_to_pfn(from.bv_page) > queue_bounce_pfn(q))
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goto bounce;
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return;
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bounce:
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bio = bio_clone_bioset(*bio_orig, GFP_NOIO, fs_bio_set);
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bio_for_each_segment_all(to, bio, i) {
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struct page *page = to->bv_page;
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if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
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continue;
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to->bv_page = mempool_alloc(pool, q->bounce_gfp);
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inc_zone_page_state(to->bv_page, NR_BOUNCE);
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if (rw == WRITE) {
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char *vto, *vfrom;
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flush_dcache_page(page);
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vto = page_address(to->bv_page) + to->bv_offset;
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vfrom = kmap_atomic(page) + to->bv_offset;
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memcpy(vto, vfrom, to->bv_len);
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kunmap_atomic(vfrom);
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}
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}
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trace_block_bio_bounce(q, *bio_orig);
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bio->bi_flags |= (1 << BIO_BOUNCED);
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if (pool == page_pool) {
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bio->bi_end_io = bounce_end_io_write;
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if (rw == READ)
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bio->bi_end_io = bounce_end_io_read;
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} else {
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bio->bi_end_io = bounce_end_io_write_isa;
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if (rw == READ)
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bio->bi_end_io = bounce_end_io_read_isa;
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}
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bio->bi_private = *bio_orig;
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*bio_orig = bio;
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}
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void blk_queue_bounce(struct request_queue *q, struct bio **bio_orig)
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{
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int must_bounce;
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mempool_t *pool;
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/*
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* Data-less bio, nothing to bounce
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*/
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if (!bio_has_data(*bio_orig))
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return;
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must_bounce = must_snapshot_stable_pages(q, *bio_orig);
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/*
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* for non-isa bounce case, just check if the bounce pfn is equal
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* to or bigger than the highest pfn in the system -- in that case,
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* don't waste time iterating over bio segments
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*/
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if (!(q->bounce_gfp & GFP_DMA)) {
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if (queue_bounce_pfn(q) >= blk_max_pfn && !must_bounce)
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return;
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pool = page_pool;
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} else {
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BUG_ON(!isa_page_pool);
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pool = isa_page_pool;
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}
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/*
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* slow path
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*/
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__blk_queue_bounce(q, bio_orig, pool, must_bounce);
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}
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EXPORT_SYMBOL(blk_queue_bounce);
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