From mboxrd@z Thu Jan 1 00:00:00 1970
From: bugzilla-daemon@bugzilla.kernel.org
Subject: [Bug 12945] SCSI Generic (sg): BUG: sleeping function called from
invalid context
Date: Thu, 26 Mar 2009 18:38:48 GMT
Message-ID: <200903261838.n2QIcmMO016095@demeter.kernel.org>
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http://bugzilla.kernel.org/show_bug.cgi?id=12945
--- Comment #2 from Tobias 2009-03-26 18:38:47 ---
On Thu, Mar 26, 2009 at 3:49 PM, Andrew Morton
wrote:
>
> (switched to email. Please respond via emailed reply-to-all, not via the
> bugzilla web interface).
>
> On Thu, 26 Mar 2009 12:27:53 GMT bugzilla-daemon@bugzilla.kernel.orgwrote:
>
> > http://bugzilla.kernel.org/show_bug.cgi?id=12945
> >
> > Summary: SCSI Generic (sg): BUG: sleeping function called from
> > invalid context
> > Product: SCSI Drivers
> > Version: 2.5
> > Kernel Version: 2.6.28.9
> > Platform: All
> > OS/Version: Linux
> > Tree: Mainline
> > Status: NEW
> > Severity: normal
> > Priority: P1
> > Component: Other
> > AssignedTo: scsi_drivers-other@kernel-bugs.osdl.org
> > ReportedBy: txtoxtox285@googlemail.com
> > Regression: No
> >
> >
> > Created an attachment (id=20685)
--> (http://bugzilla.kernel.org/attachment.cgi?id=20685)
> > --> (http://bugzilla.kernel.org/attachment.cgi?id=20685)
> > Stack trace on program kill (2.6.28.9)
> >
> > I am experimenting with CD audio extraction. I use the SCSI Generic
> driver for
> > this.
> >
> > My test program uses read() and write() (instead of ioctl) to send
> requests to
> > the driver and receive responses. I use SG_FLAG_DIRECT_IO.
> >
> > When I kill my program (because I don't want to wait until it has ripped
> the
> > entire CD), I am often rewarded with messages like "BUG: sleeping
> function
> > called from invalid context at
> linux-2.6.28.9/include/linux/pagemap.h:347". I
> > have attached typical stack trace.
> >
> > Another case when I hit this BUG is when I set a time out and the CD
> drive
> > doesn't respond fast enough. A stack trace is attached.
>
> > [34215.786870] BUG: sleeping function called from invalid context at
> /mnt/var-pub/src/linux-2.6.28.9/include/linux/pagemap.h:347
> > [34215.786880] in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper
> > [34215.786886] Pid: 0, comm: swapper Not tainted 2.6.28.9 #1
> > [34215.786890] Call Trace:
> > [34215.786894] [] set_page_dirty_lock+0x1a/0x45
> > [34215.786911] [] bio_unmap_user+0x1e/0x4a
> > [34215.786920] [] __blk_rq_unmap_user+0x14/0x20
> > [34215.786928] [] pit_next_event+0x2e/0x49
> > [34215.786934] [] blk_rq_unmap_user+0x1e/0x4b
> > [34215.786965] [] sg_finish_rem_req+0x6d/0x88 [sg]
> > [34215.786979] [] sg_rq_end_io+0x131/0x205 [sg]
> > [34215.786986] [] end_that_request_last+0x58/0x194
> > [34215.786992] [] blk_end_io+0x48/0x7d
> > [34215.787019] [] scsi_next_command+0x219/0x283
> [scsi_mod]
> > [34215.787039] [] scsi_io_completion+0x181/0x53b
> [scsi_mod]
> > [34215.787047] [] blk_done_softirq+0x5f/0x6d
> > [34215.787054] [] __do_softirq+0x5e/0xf8
> > [34215.787061] [] call_softirq+0x1c/0x28
> > [34215.787067] [] do_softirq+0x2c/0x68
> > [34215.787073] [] irq_exit+0x36/0x82
> > [34215.787079] [] do_IRQ+0xa6/0xb8
> > [34215.787085] [] ret_from_intr+0x0/0xa
> > [34215.787088] [] menu_reflect+0x0/0x6d
> > [34215.787112] [] acpi_idle_enter_simple+0x170/0x1d6
> [processor]
> > [34215.787127] [] acpi_idle_enter_simple+0x166/0x1d6
> [processor]
> > [34215.787134] [] cpuidle_idle_call+0x73/0xb1
> > [34215.787140] [] cpu_idle+0x3c/0x73
>
> Argh. sg_finish_rem_req() is called from interrupt context. But
> blk_rq_unmap_user() can run
> __bio_unmap_user()->set_page_dirty_lock()->lock_page(), which can call
> schedule(). If it does call schedule(), the machine will crash.
>
> afacit, blk_rq_unmap_user() has always been a can-sleep function, and
> this is a regression caused by
>
> commit 6e5a30cba5e7c03b2cd564e968f1dd667a0f7c42
> Author: FUJITA Tomonori
> AuthorDate: Thu Aug 28 16:17:08 2008 +0900
> Commit: Jens Axboe
> CommitDate: Thu Oct 9 08:56:10 2008 +0200
>
> sg: convert the direct IO path to use the block layer
>
> This patch converts the direct IO path (SG_FLAG_DIRECT_IO) to use the
> block layer functions (blk_get_request, blk_execute_rq_nowait,
> blk_rq_map_user, etc) instead of scsi_execute_async().
>
> Signed-off-by: FUJITA Tomonori
> Signed-off-by: Douglas Gilbert
> Cc: Mike Christie
> Cc: James Bottomley
> Signed-off-by: Jens Axboe
>
>
Andrew,
thank you for your quick response. So as a temporary workaround I will not
use direct I/O and wait for a patch.
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