From a4b869b8d113a93482d938dbac41fc1ed9a65a60 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Mar 10 2023 12:51:33 +0000
Subject: fbdev: Fix incorrect page mapping clearance at

fb_deferred_io_release() (bsc#1208266).

---

diff --git a/patches.suse/fbdev-Fix-incorrect-page-mapping-clearance-at-fb_def.patch b/patches.suse/fbdev-Fix-incorrect-page-mapping-clearance-at-fb_def.patch
new file mode 100644
index 0000000..caa13a6
--- /dev/null
+++ b/patches.suse/fbdev-Fix-incorrect-page-mapping-clearance-at-fb_def.patch
@@ -0,0 +1,92 @@
+From: Takashi Iwai <tiwai@suse.de>
+Date: Wed,  8 Mar 2023 11:50:12 +0100
+Subject: [PATCH] fbdev: Fix incorrect page mapping clearance at fb_deferred_io_release()
+Message-Id: <20230308105012.1845-1-tiwai@suse.de>
+Patch-mainline: Submitted, linux-fbdev ML
+References: bsc#1208266
+
+The recent fix for the deferred I/O by the commit
+  3efc61d95259 ("fbdev: Fix invalid page access after closing deferred I/O devices")
+caused a regression when the same fb device is opened/closed while
+it's being used.  It resulted in a frozen screen even if something
+is redrawn there after the close.  The breakage is because the patch
+was made under a wrong assumption of a single open; in the current
+code, fb_deferred_io_release() cleans up the page mapping of the
+pageref list and it calls cancel_delayed_work_sync() unconditionally,
+where both are no correct behavior for multiple opens.
+
+This patch adds a refcount for the opens of the device, and applies
+the cleanup only when all files get closed.
+
+As both fb_deferred_io_open() and _close() are called always in the
+fb_info lock (mutex), it's safe to use the normal int for the
+refcounting.
+
+Also, a useless BUG_ON() is dropped.
+
+Fixes: 3efc61d95259 ("fbdev: Fix invalid page access after closing deferred I/O devices")
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Takashi Iwai <tiwai@suse.de>
+
+---
+ drivers/video/fbdev/core/fb_defio.c |   17 +++++++++++++----
+ include/linux/fb.h                  |    1 +
+ 2 files changed, 14 insertions(+), 4 deletions(-)
+
+--- a/drivers/video/fbdev/core/fb_defio.c
++++ b/drivers/video/fbdev/core/fb_defio.c
+@@ -316,17 +316,18 @@ void fb_deferred_io_open(struct fb_info
+ 			 struct inode *inode,
+ 			 struct file *file)
+ {
++	struct fb_deferred_io *fbdefio = info->fbdefio;
++
+ 	file->f_mapping->a_ops = &fb_deferred_io_aops;
++	fbdefio->open_count++;
+ }
+ EXPORT_SYMBOL_GPL(fb_deferred_io_open);
+ 
+-void fb_deferred_io_release(struct fb_info *info)
++static void fb_deferred_io_lastclose(struct fb_info *info)
+ {
+-	struct fb_deferred_io *fbdefio = info->fbdefio;
+ 	struct page *page;
+ 	int i;
+ 
+-	BUG_ON(!fbdefio);
+ 	cancel_delayed_work_sync(&info->deferred_work);
+ 
+ 	/* clear out the mapping that we setup */
+@@ -335,13 +336,21 @@ void fb_deferred_io_release(struct fb_in
+ 		page->mapping = NULL;
+ 	}
+ }
++
++void fb_deferred_io_release(struct fb_info *info)
++{
++	struct fb_deferred_io *fbdefio = info->fbdefio;
++
++	if (!--fbdefio->open_count)
++		fb_deferred_io_lastclose(info);
++}
+ 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);
++	fb_deferred_io_lastclose(info);
+ 
+ 	kvfree(info->pagerefs);
+ 	mutex_destroy(&fbdefio->lock);
+--- a/include/linux/fb.h
++++ b/include/linux/fb.h
+@@ -212,6 +212,7 @@ struct fb_deferred_io {
+ 	/* delay between mkwrite and deferred handler */
+ 	unsigned long delay;
+ 	bool sort_pagereflist; /* sort pagelist by offset */
++	int open_count; /* number of opened files; protected by fb_info lock */
+ 	struct mutex lock; /* mutex that protects the pageref list */
+ 	struct list_head pagereflist; /* list of pagerefs for touched pages */
+ 	/* callback */
diff --git a/series.conf b/series.conf
index 844d0b9..ac7c2d9 100644
--- a/series.conf
+++ b/series.conf
@@ -37193,6 +37193,7 @@
 	########################################################
 	patches.suse/0001-firmware-sysfb-Add-parameter-to-enable-sysfb-support.patch
 	patches.suse/0001-drm-i915-gvt-fix-double-free-bug-in-split_2MB_gtt_en.patch
+	patches.suse/fbdev-Fix-incorrect-page-mapping-clearance-at-fb_def.patch
 
 	########################################################
 	# Storage