From: Sergey SENOZHATSKY <[email protected]>
`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 <[email protected]>
---
drivers/block/zram/zram_drv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index cb478ca..6f04fb2 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -738,14 +738,14 @@ 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)) {
--
2.5.3
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