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authorSergey SENOZHATSKY <sergey.senozhatsky@gmail.com>2015-11-07 03:29:04 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-07 04:50:42 +0300
commit1237275580f3e2b998d355b2ff7f84c6b423aa11 (patch)
tree24b055730587c8643d1c136a4a7d89d25e675dba /drivers
parent1d5b43bfb60f7ba2b51792978a6b0781d4ebba93 (diff)
downloadlinux-1237275580f3e2b998d355b2ff7f84c6b423aa11.tar.xz
zram: keep the exact overcommited value in mem_used_max
`mem_used_max' is designed to store the max amount of memory zram consumed to store the data. However, it does not represent the actual 'overcommited' (max) value. The existing code goes to -ENOMEM overcommited case before it updates `->stats.max_used_pages', which hides the reason we went to -ENOMEM in the first place -- we actually used more memory than `->limit_pages': alloced_pages = zs_get_total_pages(meta->mem_pool); if (zram->limit_pages && alloced_pages > zram->limit_pages) { zs_free(meta->mem_pool, handle); ret = -ENOMEM; goto out; } update_used_max(zram, alloced_pages); Which is misleading. User will see -ENOMEM, check `->limit_pages', check `->stats.max_used_pages', which will keep the value BEFORE zram passed `->limit_pages', and see: `->stats.max_used_pages' < `->limit_pages' Move update_used_max() before we do `->limit_pages' check, so that user will see: `->stats.max_used_pages' > `->limit_pages' should the overcommit and -ENOMEM happen. Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/block/zram/zram_drv.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index c93aeb876125..3e8d8ffda54d 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -726,14 +726,14 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
}
alloced_pages = zs_get_total_pages(meta->mem_pool);
+ update_used_max(zram, alloced_pages);
+
if (zram->limit_pages && alloced_pages > zram->limit_pages) {
zs_free(meta->mem_pool, handle);
ret = -ENOMEM;
goto out;
}
- update_used_max(zram, alloced_pages);
-
cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {