Messages in this thread | | | Date | Fri, 13 Jan 2012 15:28:15 +0400 | From | Sergei Shtylyov <> | Subject | Re: [PATCH] fs: Fix mod_timer crash when removing USB sticks |
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Hello.
On 12-01-2012 23:57, Paul Taysom wrote:
> From: Paul Taysom<taysom@google.com>
> A USB stick with a ext file system on it, would occasionally crash > when the stick was pulled.
> The problem was a timer was being set on the Backing Device Interface, > bdi, after the USB device had been removed and the bdi had been > unregistered. The bdi would then be later reinitialized by zeroing > the timer without removing from the timer from the timer queue. > This would eventually result in a kernel crash (NULL ptr dereference).
> When the bdi is unregistered, the dev field is set to NULL. This > indication is used by bdi_unregister to only unregister the device > once.
> Fix: When the backing device is invalidated, the mapping backing_dev_info > should be redirected to the default_backing_dev_info.
> Created 3 USB sticks with ext2, ext4 and one with both apple and DOS > file systems on it. Inserted and removed USB sticks many times in random > order. With out the bug fix, the kernel would soon crash. With the fix, > it did not. Ran on both stumpy and amd64-generic.
> Signed-off-by: Paul Taysom <taysom@chromium.org> > Downstream-bug-report: http://crosbug.com/24165 > Cc: Mandeep Baines <msb@chromium.org> > Cc: Greg KH <greg@kroah.com> > Cc: Jens Axboe <axboe@kernel.dk> > Cc: Theodore Tso <tytso@google.com> > Cc: Andrew Morton <akpm@google.com> > Cc: <linux-usb@vger.kernel.org> > Cc: <linux-kernel@vger.kernel.org> > Cc: Alexander Viro <viro@zeniv.linux.org.uk> > Cc: <linux-fsdevel@vger.kernel.org> > --- > fs/block_dev.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-)
> diff --git a/fs/block_dev.c b/fs/block_dev.c > index afe74dd..9f9b617 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -1,4 +1,4 @@ > -/* > +nvalid/*
Huh?
> * linux/fs/block_dev.c > * > * Copyright (C) 1991, 1992 Linus Torvalds
WBR, Sergei
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