Re: Memory leak on UBI volume truncating

[Artem Bityutskiy <dedekind1@gmail.com>]

On Mon, 2010-01-18 at 09:36 +0100, Marek Skuczynski wrote:
> Hello Artem,
> > On Sun, Jan 17, 2010 at 11:43 AM, Artem Bityutskiy <dedekind1@gmail.com> wrote:
> >> On Sun, 2010-01-17 at 12:37 +0200, Artem Bityutskiy wrote:
> >>> Hi,
> >>>
> >>> On Wed, 2010-01-13 at 15:28 +0100, Marek Skuczynski wrote:
> >>> > Hello,
> >>> >   I have prepare a simple volume update stress test (see test code below).
> >>> >   This test has been run for kernel 2.6.23 with some updates from 2.6.28,
> >>> >   and always after a few minutes the OOM killer was launched.
> >>> >
> >>> >   What i found it that each an UBI volume truncate operation with
> >>> > ubiupdatevol tool
> >>> >   causes memory leak. I think this happens because:
> >>> >
> >>> >   - ubi_start_update()  param "bytes" is equal 0
> >>> >
> >>> >   - vol->updating flag is re-set to 0
> >>> >
> >>> >   - vol->upd_buf is allocated regardless of vol->updating flag,
> >>> >      but not released on device close by vol_cdev_release()
> >>> >
> >>> >   I never run the test on a newer kernel version, so I cannot confirm
> >>> > that this problem still exists.
> >>> >
> >>> >   Please confirm, whether my findings are correct or not, thanks.
> >>>
> >>> thanks for this finding. Looks like your analysis is right. Does this
> >>> simple patch help?
> >>
> >> Actually this even simpler patch should fix the issue. Could you please
> >> test it and let me know if it helps.
> >>
> >> diff --git a/drivers/mtd/ubi/upd.c b/drivers/mtd/ubi/upd.c
> >> index c1d7b88..425bf5a 100644
> >> --- a/drivers/mtd/ubi/upd.c
> >> +++ b/drivers/mtd/ubi/upd.c
> >> @@ -155,6 +155,7 @@ int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
> >>                if (err)
> >>                        return err;
> >>                vol->updating = 0;
> >> +               return 0;
> >>        }
> >>
> >>        vol->upd_buf = vmalloc(ubi->leb_size);
> >>
> >> --
> 
> Thanks for you reply. It seems the fix solve the issue.

Cool. I'll push the fix and also send it to -stable a bit later. Thanks
for catching this.

-- 
Best Regards,
Artem Bityutskiy (Артём Битюцкий)