linux-kernel - Re: [PATCHv4 00/10] add on-demand device creation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 6 May 2015 17:10:29 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:	Minchan Kim <minchan@...nel.org>
Cc:	Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
	Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv4 00/10] add on-demand device creation

On (05/06/15 16:28), Minchan Kim wrote:
> > 
> > from your logs:
> > ...
> > [ 98.756017] zram: Removed device: zram2
> > [ 98.757087] ------------[ cut here ]------------
> > ...
> > 
> > locked zram_index_mutex, removed zram2, unlocked zram_index_mutex,
> > locked zram_index_mutex, attempted to create zram2: zram2 sysfs already exist.
> > 
> > 
> > hm... need to think. zram hot/remove is serialized.
> 
> I never look at the code but I doubt others(ex, some admin process on my machine)
> holds a ref so kobj doesn't disapper yet but zram_add try to create it?
> 

well, something like this is certainly happening. hm, if this is the
case, then a very quick thing I can think of is to stop re-using previously
used zram ids. add_disk() doesn't give us a chance to handle any errors and
testing for sysfs leftovers in zram_add() looks weird.


btw, do you also want me to rename zram-control sysfs handlers?
zram_add -> zram_hot_add() ? i think zram_add()/zram_remove() is just
ok.



can you please test this patch?

---

 drivers/block/zram/zram_drv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index e6c4316..b31f0c20 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -1184,7 +1184,7 @@ static int zram_add(void)
 	if (!zram)
 		return -ENOMEM;
 
-	ret = idr_alloc(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
+	ret = idr_alloc_cyclic(&zram_index_idr, zram, 0, 0, GFP_KERNEL);
 	if (ret < 0)
 		goto out_free_dev;
 	device_id = ret;
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/