Messages in this thread | | | Date | Mon, 16 Jan 2012 13:53:54 +0800 | From | Wu Fengguang <> | Subject | Re: [PATCH] mm/backing-dev.c: fix crash when USB/SCSI device is detached |
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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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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