From: Minchan Kim <minchan@kernel.org>
To: zhouxianrong <zhouxianrong@huawei.com>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<akpm@linux-foundation.org>, <sergey.senozhatsky@gmail.com>,
<willy@infradead.org>, <iamjoonsoo.kim@lge.com>,
<ngupta@vflare.org>, <Mi.Sophia.Wang@huawei.com>,
<zhouxiyu@huawei.com>, <weidu.du@huawei.com>,
<zhangshiming5@huawei.com>, <won.ho.park@huawei.com>
Subject: Re: [PATCH] mm: extend zero pages to same element pages for zram
Date: Tue, 7 Feb 2017 11:54:26 +0900 [thread overview]
Message-ID: <20170207025426.GA1528@bbox> (raw)
In-Reply-To: <ba64f168-72f5-65c3-c88c-7a59e57b20aa@huawei.com>
On Tue, Feb 07, 2017 at 10:20:57AM +0800, zhouxianrong wrote:
< snip >
> >>3. the below should be modified.
> >>
> >>static inline bool zram_meta_get(struct zram *zram)
> >>@@ -495,11 +553,17 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize)
> >>
> >> /* Free all pages that are still in this zram device */
> >> for (index = 0; index < num_pages; index++) {
> >>- unsigned long handle = meta->table[index].handle;
> >>+ unsigned long handle;
> >>+
> >>+ bit_spin_lock(ZRAM_ACCESS, &meta->table[index].value);
> >>+ handle = meta->table[index].handle;
> >>
> >>- if (!handle)
> >>+ if (!handle || zram_test_flag(meta, index, ZRAM_SAME)) {
> >>+ bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
> >> continue;
> >>+ }
> >>
> >>+ bit_spin_unlock(ZRAM_ACCESS, &meta->table[index].value);
> >> zs_free(meta->mem_pool, handle);
> >
> >Could you explain why we need this modification?
> >
> >> }
> >>
> >>@@ -511,7 +575,7 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize)
> >> static struct zram_meta *zram_meta_alloc(char *pool_name, u64 disksize)
> >> {
> >> size_t num_pages;
> >>- struct zram_meta *meta = kmalloc(sizeof(*meta), GFP_KERNEL);
> >>+ struct zram_meta *meta = kzalloc(sizeof(*meta), GFP_KERNEL);
> >
> >Ditto
> >
> >>
> >>
> >
> >.
> >
>
> because of union of handle and element, i think a non-zero element (other than handle) is prevented from freeing.
> if zram_meta_get was modified, zram_meta_alloc did so.
Right. Thanks but I don't see why we need the locking in there and modification of
zram_meta_alloc.
Isn't it enough with this?
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index c20b05a84f21..a25d34a8af19 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -425,8 +425,11 @@ static void zram_meta_free(struct zram_meta *meta, u64 disksize)
/* Free all pages that are still in this zram device */
for (index = 0; index < num_pages; index++) {
unsigned long handle = meta->table[index].handle;
-
- if (!handle)
+ /*
+ * No memory is allocated for same element filled pages.
+ * Simply clear same page flag.
+ */
+ if (!handle || zram_test_flag(meta, index, ZRAM_SAME))
continue;
zs_free(meta->mem_pool, handle);
next prev parent reply other threads:[~2017-02-07 2:54 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-06 8:42 [PATCH] mm: extend zero pages to same element pages for zram zhouxianrong
2017-01-09 23:41 ` Minchan Kim
2017-01-13 4:24 ` Sergey Senozhatsky
2017-01-13 6:23 ` Minchan Kim
2017-01-13 6:36 ` Sergey Senozhatsky
2017-01-13 6:47 ` Minchan Kim
2017-01-13 7:02 ` Sergey Senozhatsky
2017-01-13 8:03 ` Minchan Kim
2017-01-13 8:29 ` zhouxianrong
2017-01-21 8:43 ` Sergey Senozhatsky
2017-01-22 2:58 ` zhouxianrong
2017-01-22 4:45 ` Sergey Senozhatsky
2017-01-23 2:58 ` Joonsoo Kim
2017-01-23 3:32 ` zhouxianrong
2017-01-23 4:03 ` Sergey Senozhatsky
2017-01-23 6:27 ` Joonsoo Kim
2017-01-23 7:13 ` Sergey Senozhatsky
2017-01-23 7:40 ` Minchan Kim
2017-01-24 7:58 ` zhouxianrong
2017-01-25 1:29 ` Minchan Kim
2017-01-25 1:32 ` Sergey Senozhatsky
2017-01-25 2:48 ` Matthew Wilcox
2017-01-25 4:18 ` Sergey Senozhatsky
2017-01-25 4:51 ` Minchan Kim
2017-01-25 5:38 ` Sergey Senozhatsky
2017-01-25 5:44 ` Minchan Kim
2017-01-23 6:26 ` Matthew Wilcox
2017-01-23 6:32 ` 答复: " zhouxianrong
2017-02-03 8:34 ` zhouxianrong
2017-02-03 8:42 ` zhouxianrong
2017-02-03 15:33 ` Matthew Wilcox
2017-02-04 3:33 ` zhouxianrong
2017-02-05 14:21 ` Minchan Kim
2017-02-06 1:28 ` zhouxianrong
2017-02-06 14:14 ` Matthew Wilcox
2017-02-06 23:48 ` Minchan Kim
2017-02-07 2:20 ` zhouxianrong
2017-02-07 2:54 ` Minchan Kim [this message]
2017-02-07 3:24 ` zhouxianrong
2017-02-07 4:57 ` Minchan Kim
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170207025426.GA1528@bbox \
--to=minchan@kernel.org \
--cc=Mi.Sophia.Wang@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=iamjoonsoo.kim@lge.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=ngupta@vflare.org \
--cc=sergey.senozhatsky@gmail.com \
--cc=weidu.du@huawei.com \
--cc=willy@infradead.org \
--cc=won.ho.park@huawei.com \
--cc=zhangshiming5@huawei.com \
--cc=zhouxianrong@huawei.com \
--cc=zhouxiyu@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).