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Message-ID: <20230128213140.b54wgvupuldexvzk@workstation> Date: Sat, 28 Jan 2023 22:31:40 +0100 From: Patrik Jakobsson <pjakobsson@...e.de> To: Takashi Iwai <tiwai@...e.de> Cc: Helge Deller <deller@....de>, linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, Thomas Zimmermann <tzimmermann@...e.de> Subject: Re: [PATCH] fbdev: Fix invalid page access after closing deferred I/O devices On Fri, Jan 27, 2023 at 05:58:34PM +0100, Takashi Iwai wrote: > When a fbdev with deferred I/O is once opened and closed, the dirty > pages still remain queued in the pageref list, and eventually later > those may be processed in the delayed work. This may lead to a > corruption of pages, hitting an Oops. > > This patch makes sure to cancel the delayed work and clean up the > pageref list at closing the device for addressing the bug. A part of > the cleanup code is factored out as a new helper function that is > called from the common fb_release(). > > Cc: <stable@...r.kernel.org> > Signed-off-by: Takashi Iwai <tiwai@...e.de> Reviewed-by: Patrik Jakobsson <pjakobsson@...e.de> > --- > drivers/video/fbdev/core/fb_defio.c | 10 +++++++++- > drivers/video/fbdev/core/fbmem.c | 2 ++ > include/linux/fb.h | 1 + > 3 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c > index c730253ab85c..583cbcf09446 100644 > --- a/drivers/video/fbdev/core/fb_defio.c > +++ b/drivers/video/fbdev/core/fb_defio.c > @@ -313,7 +313,7 @@ void fb_deferred_io_open(struct fb_info *info, > } > EXPORT_SYMBOL_GPL(fb_deferred_io_open); > > -void fb_deferred_io_cleanup(struct fb_info *info) > +void fb_deferred_io_release(struct fb_info *info) > { > struct fb_deferred_io *fbdefio = info->fbdefio; > struct page *page; > @@ -327,6 +327,14 @@ void fb_deferred_io_cleanup(struct fb_info *info) > page = fb_deferred_io_page(info, i); > page->mapping = NULL; > } > +} > +EXPORT_SYMBOL_GPL(fb_deferred_io_release); > + > +void fb_deferred_io_cleanup(struct fb_info *info) > +{ > + struct fb_deferred_io *fbdefio = info->fbdefio; > + > + fb_deferred_io_release(info); > > kvfree(info->pagerefs); > mutex_destroy(&fbdefio->lock); > diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c > index 3a6c8458eb8d..78c4cb5ee7c9 100644 > --- a/drivers/video/fbdev/core/fbmem.c > +++ b/drivers/video/fbdev/core/fbmem.c > @@ -1454,6 +1454,8 @@ __releases(&info->lock) > struct fb_info * const info = file->private_data; > > lock_fb_info(info); > + if (info->fbdefio) > + fb_deferred_io_release(info); > if (info->fbops->fb_release) > info->fbops->fb_release(info,1); > module_put(info->fbops->owner); > diff --git a/include/linux/fb.h b/include/linux/fb.h > index 96b96323e9cb..73eb1f85ea8e 100644 > --- a/include/linux/fb.h > +++ b/include/linux/fb.h > @@ -662,6 +662,7 @@ extern int fb_deferred_io_init(struct fb_info *info); > extern void fb_deferred_io_open(struct fb_info *info, > struct inode *inode, > struct file *file); > +extern void fb_deferred_io_release(struct fb_info *info); > extern void fb_deferred_io_cleanup(struct fb_info *info); > extern int fb_deferred_io_fsync(struct file *file, loff_t start, > loff_t end, int datasync); > -- > 2.35.3 >
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