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block:bounce: fix call inc_|dec_zone_page_state on different pages confuse value of NR_BOUNCE

PATCH Applied Wang YanQing 2 participants 2 messages Apr 26, 2015 – Apr 27, 2015

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PATCH v2 1/1 block:bounce: fix call inc_|dec_zone_page_state on different pages confuse value of NR_BOUNCE

Commit d2c5e30c9a1420902262aa923794d2ae4e0bc391
("[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.

---
Changes
v1-v2: fix comment issue reported by Leon Romanovsky

 block/bounce.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
block/bounce.c +1 -1
index ab21ba2..ed9dd80 100644
@@ -221,8 +221,8 @@ bounce:
 		if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
 			continue;
 
-		inc_zone_page_state(to->bv_page, NR_BOUNCE);
 		to->bv_page = mempool_alloc(pool, q->bounce_gfp);
+		inc_zone_page_state(to->bv_page, NR_BOUNCE);
 
 		if (rw == WRITE) {
 			char *vto, *vfrom;
Signature · 7 lines
1.8.5.6.2.g3d8a54e.dirty

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maintainer Applied
#1 lore raw
Quoted 47 lines · Wang YanQing

Commit d2c5e30c9a1420902262aa923794d2ae4e0bc391
("[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.

---
Changes
v1-v2: fix comment issue reported by Leon Romanovsky

  block/bounce.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)
block/bounce.c +0 -0
index ab21ba2..ed9dd80 100644

block/bounce.c bounce: · line 228

Quoted 9 lines
block/bounce.c +1 -1
@@ -221,8 +221,8 @@ bounce:
  		if (page_to_pfn(page) <= queue_bounce_pfn(q) && !force)
  			continue;
 
-		inc_zone_page_state(to->bv_page, NR_BOUNCE);
  		to->bv_page = mempool_alloc(pool, q->bounce_gfp);
+		inc_zone_page_state(to->bv_page, NR_BOUNCE);
 
  		if (rw == WRITE) {
  			char *vto, *vfrom;

Applied, thanks.

Signature · 7 lines
Jens Axboe

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