From: Wu Fengguang <fengguang.wu@intel.com>
To: Chanho Min <chanho0207@gmail.com>
Cc: Rabin Vincent <rabin@rab.in>, Jens Axboe <axboe@kernel.dk>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/backing-dev.c: fix crash when USB/SCSI device is detached
Date: Mon, 16 Jan 2012 13:53:54 +0800 [thread overview]
Message-ID: <20120116055354.GA15265@localhost> (raw)
In-Reply-To: <20120116055044.GA14857@localhost>
On Mon, Jan 16, 2012 at 01:50:44PM +0800, Wu Fengguang wrote:
> On Mon, Jan 16, 2012 at 02:28:30PM +0900, Chanho Min wrote:
> > On Mon, Jan 16, 2012 at 11:53 AM, Wu Fengguang <fengguang.wu@intel.com> wrote:
> > > On Sun, Jan 15, 2012 at 09:11:07PM +0530, Rabin Vincent wrote:
> > >> On Sun, Jan 15, 2012 at 08:58:53PM +0800, Wu Fengguang wrote:
> > >> > On Sun, Jan 15, 2012 at 03:58:43PM +0530, Rabin Vincent wrote:
> > >> > > diff --git a/mm/backing-dev.c b/mm/backing-dev.c
> > >> > > index 71034f4..a39ad70 100644
> > >> > > --- a/mm/backing-dev.c
> > >> > > +++ b/mm/backing-dev.c
> > >> > > @@ -318,7 +318,7 @@ static void wakeup_timer_fn(unsigned long data)
> > >> > > if (bdi->wb.task) {
> > >> > > trace_writeback_wake_thread(bdi);
> > >> > > wake_up_process(bdi->wb.task);
> > >> > > - } else {
> > >> > > + } else if (bdi->dev) {
> > >> > > /*
> > >> > > * When bdi tasks are inactive for long time, they are killed.
> > >> > > * In this case we have to wake-up the forker thread which
> > >> > > @@ -584,6 +584,8 @@ EXPORT_SYMBOL(bdi_register_dev);
> > >> > > */
> > >> > > static void bdi_wb_shutdown(struct backing_dev_info *bdi)
> > >> > > {
> > >> > > + struct task_struct *task = NULL;
> >
> > Thanks, I fully understand.
> > In addition, Would not bdi_wakeup_flusher also be fixed?
>
> Yes, indeed!
But wait.. Rabin's patch actually fixes the NULL deference in
the call
trace_writeback_wake_forker_thread(bdi);
The wakeup of the forker thread should be harmless.
Thanks,
Fengguang
> > >From dc7d4e86911c0a7ea35043485b04e8a09aa74ffd Mon Sep 17 00:00:00 2001
> > From: Chanho Min <chanho.min@lge.com>
> > Date: Mon, 16 Jan 2012 14:14:48 +0900
> > Subject: [PATCH] backing-dev: add for 'fix wakeup timer races with
> > bdi_unregister()'
> >
> > Signed-off-by: Chanho Min <chanho.min@lge.com>
> > ---
> > fs/fs-writeback.c | 2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> > index f855916..ee40833 100644
> > --- a/fs/fs-writeback.c
> > +++ b/fs/fs-writeback.c
> > @@ -97,7 +97,7 @@ static void bdi_wakeup_flusher(struct backing_dev_info *bdi)
> > {
> > if (bdi->wb.task) {
> > wake_up_process(bdi->wb.task);
> > - } else {
> > + } else if (bdi->dev) {
> > /*
> > * The bdi thread isn't there, wake up the forker thread which
> > * will create and run it.
> > --
> > 1.7.0.4
next prev parent reply other threads:[~2012-01-16 5:53 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-05 8:49 [PATCH] mm/backing-dev.c: fix crash when USB/SCSI device is detached Chanho Min
2012-01-15 10:28 ` Rabin Vincent
2012-01-15 12:58 ` Wu Fengguang
2012-01-15 15:41 ` Rabin Vincent
2012-01-16 2:53 ` Wu Fengguang
2012-01-16 5:28 ` Chanho Min
2012-01-16 5:50 ` Wu Fengguang
2012-01-16 5:53 ` Wu Fengguang [this message]
2012-01-16 6:34 ` Chanho Min
2012-01-18 19:43 ` Rabin Vincent
2012-01-19 16:50 ` [PATCHv2] backing-dev: fix wakeup timer races with bdi_unregister() Rabin Vincent
2012-01-19 23:46 ` Namjae Jeon
2012-01-20 5:24 ` Rabin Vincent
2012-01-20 6:15 ` Namjae Jeon
2012-01-20 10:03 ` Rabin Vincent
2012-01-20 11:18 ` Namjae Jeon
2012-01-20 12:08 ` Rabin Vincent
2012-01-20 15:04 ` Namjae Jeon
2012-01-31 13:24 ` Wu Fengguang
[not found] <004401ccc932$444a0070$ccde0150$@min@lge.com>
2012-01-02 9:57 ` [PATCH] mm/backing-dev.c: fix crash when USB/SCSI device is detached Wu Fengguang
[not found] ` <002e01ccc9c7$1928c940$4b7a5bc0$@min@lge.com>
2012-01-03 4:49 ` Wu Fengguang
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