From: Oliver Neukum <oneukum@suse.de>
To: Ming Lei <ming.lei@canonical.com>
Cc: Alan Stern <stern@rowland.harvard.edu>,
linux-kernel@vger.kernel.org, Minchan Kim <minchan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rjw@sisk.pl>, Jens Axboe <axboe@kernel.dk>,
"David S. Miller" <davem@davemloft.net>,
Andrew Morton <akpm@linux-foundation.org>,
netdev@vger.kernel.org, linux-usb@vger.kernel.org,
linux-pm@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH v3 2/6] PM / Runtime: introduce pm_runtime_set[get]_memalloc_noio()
Date: Tue, 30 Oct 2012 17:30:13 +0100 [thread overview]
Message-ID: <2504263.kbM6W9JoH9@linux-lqwf.site> (raw)
In-Reply-To: <CACVXFVO5-UPNrWsySzDE5AfOv1TMqbyitQX9ViidSJPM36fqAQ@mail.gmail.com>
On Wednesday 31 October 2012 00:00:56 Ming Lei wrote:
> On Tue, Oct 30, 2012 at 11:38 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
>
> >
> > Okay, I see your point. But acquiring the lock here doesn't solve the
> > problem. Suppose a thread is about to reset a USB mass-storage device.
> > It acquires the lock and sees that the noio flag is clear. But before
> > it can issue the reset, another thread sets the noio flag.
>
> If the USB mass-storage device is being reseted, the flag should be set
> already generally. If the flag is still unset, that means the disk/network
> device isn't added into system(or removed just now), so memory allocation
> with block I/O should be allowed during the reset. Looks it isn't one problem,
> isn't it?
I am afraid it is, because a disk may just have been probed as the deviceis being reset.
Regards
Oliver
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next prev parent reply other threads:[~2012-10-30 16:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-29 12:23 [PATCH v3 0/6] solve deadlock caused by memory allocation with I/O Ming Lei
2012-10-29 12:23 ` [PATCH v3 1/6] mm: teach mm by current context info to not do I/O during memory allocation Ming Lei
2012-10-29 12:23 ` [PATCH v3 2/6] PM / Runtime: introduce pm_runtime_set[get]_memalloc_noio() Ming Lei
2012-10-29 15:41 ` Alan Stern
2012-10-30 3:21 ` Ming Lei
2012-10-30 10:57 ` Oliver Neukum
2012-10-30 11:30 ` Ming Lei
2012-10-30 15:38 ` Alan Stern
2012-10-30 16:00 ` Ming Lei
2012-10-30 16:15 ` Ming Lei
2012-10-30 16:30 ` Oliver Neukum [this message]
2012-10-31 2:08 ` Ming Lei
2012-10-31 3:05 ` Ming Lei
2012-10-31 8:37 ` Oliver Neukum
2012-10-31 15:20 ` Alan Stern
2012-10-31 15:41 ` Alan Stern
2012-10-31 23:18 ` Ming Lei
2012-10-30 16:54 ` Alan Stern
2012-10-29 12:23 ` [PATCH v3 3/6] block/genhd.c: apply pm_runtime_set_memalloc_noio on block devices Ming Lei
2012-10-29 12:23 ` [PATCH v3 4/6] net/core: apply pm_runtime_set_memalloc_noio on network devices Ming Lei
2012-10-29 15:44 ` Alan Stern
2012-10-29 12:23 ` [PATCH v3 5/6] PM / Runtime: force memory allocation with no I/O during runtime_resume callbcack Ming Lei
2012-10-29 12:24 ` [PATCH v3 6/6] USB: forbid memory allocation with I/O during bus reset Ming Lei
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