When vm.dirtytime_expire_seconds is set to 0, wakeup_dirtytime_writeback()
schedules delayed work with a delay of 0, causing immediate execution.
The function then reschedules itself with 0 delay again, creating an
infinite busy loop that causes 100% kworker CPU usage.
Fix by:
- Only scheduling delayed work in wakeup_dirtytime_writeback() when
dirtytime_expire_interval is non-zero
- Cancelling the delayed work in dirtytime_interval_handler() when
the interval is set to 0
- Adding a guard in start_dirtytime_writeback() for defensive coding
Tested by booting kernel in QEMU with virtme-ng:
- Before fix: kworker CPU spikes to ~73%
- After fix: CPU remains at normal levels
- Setting interval back to non-zero correctly resumes writeback
Fixes: a2f4870697a5 ("fs: make sure the timestamps for lazytime inodes eventually get written")
Cc: stable(a)vger.kernel.org
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220227
Signed-off-by: Laveesh Bansal <laveeshb(a)laveeshbansal.com>
---
fs/fs-writeback.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 6800886c4d10..cd21c74cd0e5 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -2492,7 +2492,8 @@ static void wakeup_dirtytime_writeback(struct work_struct *w)
wb_wakeup(wb);
}
rcu_read_unlock();
- schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
+ if (dirtytime_expire_interval)
+ schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
}
static int dirtytime_interval_handler(const struct ctl_table *table, int write,
@@ -2501,8 +2502,12 @@ static int dirtytime_interval_handler(const struct ctl_table *table, int write,
int ret;
ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
- if (ret == 0 && write)
- mod_delayed_work(system_percpu_wq, &dirtytime_work, 0);
+ if (ret == 0 && write) {
+ if (dirtytime_expire_interval)
+ mod_delayed_work(system_percpu_wq, &dirtytime_work, 0);
+ else
+ cancel_delayed_work_sync(&dirtytime_work);
+ }
return ret;
}
@@ -2519,7 +2524,8 @@ static const struct ctl_table vm_fs_writeback_table[] = {
static int __init start_dirtytime_writeback(void)
{
- schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
+ if (dirtytime_expire_interval)
+ schedule_delayed_work(&dirtytime_work, dirtytime_expire_interval * HZ);
register_sysctl_init("vm", vm_fs_writeback_table);
return 0;
}
--
2.43.0
Dear linux-fbdev, stable,
On Mon, Oct 20, 2025 at 09:47:01PM +0800, Junjie Cao wrote:
> bit_putcs_aligned()/unaligned() derived the glyph pointer from the
> character value masked by 0xff/0x1ff, which may exceed the actual font's
> glyph count and read past the end of the built-in font array.
> Clamp the index to the actual glyph count before computing the address.
>
> This fixes a global out-of-bounds read reported by syzbot.
>
> Reported-by: syzbot+793cf822d213be1a74f2(a)syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=793cf822d213be1a74f2
> Tested-by: syzbot+793cf822d213be1a74f2(a)syzkaller.appspotmail.com
> Signed-off-by: Junjie Cao <junjie.cao(a)intel.com>
This commit is applied to v5.10.247 and causes a regression: when
switching VT with ctrl-alt-f2 the screen is blank or completely filled
with angle characters, then new text is not appearing (or not visible).
This commit is found with git bisect from v5.10.246 to v5.10.247:
0998a6cb232674408a03e8561dc15aa266b2f53b is the first bad commit
commit 0998a6cb232674408a03e8561dc15aa266b2f53b
Author: Junjie Cao <junjie.cao(a)intel.com>
AuthorDate: 2025-10-20 21:47:01 +0800
Commit: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
CommitDate: 2025-12-07 06:08:07 +0900
fbdev: bitblit: bound-check glyph index in bit_putcs*
commit 18c4ef4e765a798b47980555ed665d78b71aeadf upstream.
bit_putcs_aligned()/unaligned() derived the glyph pointer from the
character value masked by 0xff/0x1ff, which may exceed the actual font's
glyph count and read past the end of the built-in font array.
Clamp the index to the actual glyph count before computing the address.
This fixes a global out-of-bounds read reported by syzbot.
Reported-by: syzbot+793cf822d213be1a74f2(a)syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=793cf822d213be1a74f2
Tested-by: syzbot+793cf822d213be1a74f2(a)syzkaller.appspotmail.com
Signed-off-by: Junjie Cao <junjie.cao(a)intel.com>
Reviewed-by: Thomas Zimmermann <tzimmermann(a)suse.de>
Signed-off-by: Helge Deller <deller(a)gmx.de>
Cc: stable(a)vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org>
drivers/video/fbdev/core/bitblit.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
The minimal reproducer in cli, after kernel is booted:
date >/dev/tty2; chvt 2
and the date does not appear.
Thanks,
#regzbot introduced: 0998a6cb232674408a03e8561dc15aa266b2f53b
> ---
> v1: https://lore.kernel.org/linux-fbdev/5d237d1a-a528-4205-a4d8-71709134f1e1@su…
> v1 -> v2:
> - Fix indentation and add blank line after declarations with the .pl helper
> - No functional changes
>
> drivers/video/fbdev/core/bitblit.c | 16 ++++++++++++----
> 1 file changed, 12 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/video/fbdev/core/bitblit.c b/drivers/video/fbdev/core/bitblit.c
> index 9d2e59796c3e..085ffb44c51a 100644
> --- a/drivers/video/fbdev/core/bitblit.c
> +++ b/drivers/video/fbdev/core/bitblit.c
> @@ -79,12 +79,16 @@ static inline void bit_putcs_aligned(struct vc_data *vc, struct fb_info *info,
> struct fb_image *image, u8 *buf, u8 *dst)
> {
> u16 charmask = vc->vc_hi_font_mask ? 0x1ff : 0xff;
> + unsigned int charcnt = vc->vc_font.charcount;
> u32 idx = vc->vc_font.width >> 3;
> u8 *src;
>
> while (cnt--) {
> - src = vc->vc_font.data + (scr_readw(s++)&
> - charmask)*cellsize;
> + u16 ch = scr_readw(s++) & charmask;
> +
> + if (ch >= charcnt)
> + ch = 0;
> + src = vc->vc_font.data + (unsigned int)ch * cellsize;
>
> if (attr) {
> update_attr(buf, src, attr, vc);
> @@ -112,14 +116,18 @@ static inline void bit_putcs_unaligned(struct vc_data *vc,
> u8 *dst)
> {
> u16 charmask = vc->vc_hi_font_mask ? 0x1ff : 0xff;
> + unsigned int charcnt = vc->vc_font.charcount;
> u32 shift_low = 0, mod = vc->vc_font.width % 8;
> u32 shift_high = 8;
> u32 idx = vc->vc_font.width >> 3;
> u8 *src;
>
> while (cnt--) {
> - src = vc->vc_font.data + (scr_readw(s++)&
> - charmask)*cellsize;
> + u16 ch = scr_readw(s++) & charmask;
> +
> + if (ch >= charcnt)
> + ch = 0;
> + src = vc->vc_font.data + (unsigned int)ch * cellsize;
>
> if (attr) {
> update_attr(buf, src, attr, vc);
> --
> 2.48.1
>
Xorg fails to start with defaults on AMD KV260, /var/log/Xorg.0.log:
[ 23.491] (II) Loading /usr/lib/xorg/modules/drivers/fbdev_drv.so
[ 23.491] (II) Module fbdev: vendor="X.Org Foundation"
[ 23.491] compiled for 1.21.1.18, module version = 0.5.1
[ 23.491] Module class: X.Org Video Driver
[ 23.491] ABI class: X.Org Video Driver, version 25.2
[ 23.491] (II) modesetting: Driver for Modesetting Kernel Drivers:
kms
[ 23.491] (II) FBDEV: driver for framebuffer: fbdev
[ 23.510] (II) modeset(0): using drv /dev/dri/card1
[ 23.511] (WW) Falling back to old probe method for fbdev
[ 23.511] (II) Loading sub module "fbdevhw"
[ 23.511] (II) LoadModule: "fbdevhw"
[ 23.511] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[ 23.511] (II) Module fbdevhw: vendor="X.Org Foundation"
[ 23.511] compiled for 1.21.1.18, module version = 0.0.2
[ 23.511] ABI class: X.Org Video Driver, version 25.2
[ 23.512] (II) modeset(0): Creating default Display subsection in
Screen section
"Default Screen Section" for depth/fbbpp 24/32
[ 23.512] (==) modeset(0): Depth 24, (==) framebuffer bpp 32
[ 23.512] (==) modeset(0): RGB weight 888
[ 23.512] (==) modeset(0): Default visual is TrueColor
...
[ 23.911] (II) Loading sub module "fb"
[ 23.911] (II) LoadModule: "fb"
[ 23.911] (II) Module "fb" already built-in
[ 23.911] (II) UnloadModule: "fbdev"
[ 23.911] (II) Unloading fbdev
[ 23.912] (II) UnloadSubModule: "fbdevhw"
[ 23.912] (II) Unloading fbdevhw
[ 24.238] (==) modeset(0): Backing store enabled
[ 24.238] (==) modeset(0): Silken mouse enabled
[ 24.249] (II) modeset(0): Initializing kms color map for depth 24, 8
bpc.
[ 24.250] (==) modeset(0): DPMS enabled
[ 24.250] (II) modeset(0): [DRI2] Setup complete
[ 24.250] (II) modeset(0): [DRI2] DRI driver: kms_swrast
[ 24.250] (II) modeset(0): [DRI2] VDPAU driver: kms_swrast
...
[ 24.770] (II) modeset(0): Disabling kernel dirty updates, not
required.
[ 24.770] (EE) modeset(0): failed to set mode: Invalid argument
xorg tries to use 24 and 32 bpp which pass on the fb API but which
don't actually work on AMD KV260 when Xorg starts. As a workaround
Xorg config can set color depth to 16 using /etc/X11/xorg.conf snippet:
Section "Screen"
Identifier "Default Screen"
Monitor "Configured Monitor"
Device "Configured Video Device"
DefaultDepth 16
EndSection
But this is cumbersome on images meant for multiple different arm64
devices and boards. So instead set 16 bpp as preferred depth
in zynqmp_kms fb driver which is used by Xorg in the logic to find
out a working depth.
Now Xorg startup and bpp query using fb API works and HDMI display
shows graphics. /var/log/Xorg.0.log shows:
[ 23.219] (II) LoadModule: "fbdev"
[ 23.219] (II) Loading /usr/lib/xorg/modules/drivers/fbdev_drv.so
[ 23.219] (II) Module fbdev: vendor="X.Org Foundation"
[ 23.219] compiled for 1.21.1.18, module version = 0.5.1
[ 23.219] Module class: X.Org Video Driver
[ 23.219] ABI class: X.Org Video Driver, version 25.2
[ 23.219] (II) modesetting: Driver for Modesetting Kernel Drivers:
kms
[ 23.219] (II) FBDEV: driver for framebuffer: fbdev
[ 23.238] (II) modeset(0): using drv /dev/dri/card1
[ 23.238] (WW) Falling back to old probe method for fbdev
[ 23.238] (II) Loading sub module "fbdevhw"
[ 23.238] (II) LoadModule: "fbdevhw"
[ 23.239] (II) Loading /usr/lib/xorg/modules/libfbdevhw.so
[ 23.239] (II) Module fbdevhw: vendor="X.Org Foundation"
[ 23.239] compiled for 1.21.1.18, module version = 0.0.2
[ 23.239] ABI class: X.Org Video Driver, version 25.2
[ 23.240] (II) modeset(0): Creating default Display subsection in Screen section
"Default Screen Section" for depth/fbbpp 16/16
[ 23.240] (==) modeset(0): Depth 16, (==) framebuffer bpp 16
[ 23.240] (==) modeset(0): RGB weight 565
[ 23.240] (==) modeset(0): Default visual is TrueColor
...
[ 24.015] (==) modeset(0): Backing store enabled
[ 24.015] (==) modeset(0): Silken mouse enabled
[ 24.027] (II) modeset(0): Initializing kms color map for depth 16, 6 bpc.
[ 24.028] (==) modeset(0): DPMS enabled
[ 24.028] (II) modeset(0): [DRI2] Setup complete
[ 24.028] (II) modeset(0): [DRI2] DRI driver: kms_swrast
[ 24.028] (II) modeset(0): [DRI2] VDPAU driver: kms_swrast
Cc: Bill Mills <bill.mills(a)linaro.org>
Cc: Ilias Apalodimas <ilias.apalodimas(a)linaro.org>
Cc: Anatoliy Klymenko <anatoliy.klymenko(a)amd.com>
Cc: stable(a)vger.kernel.org
Signed-off-by: Mikko Rapeli <mikko.rapeli(a)linaro.org>
---
drivers/gpu/drm/xlnx/zynqmp_kms.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_kms.c b/drivers/gpu/drm/xlnx/zynqmp_kms.c
index ccc35cacd10cb..a42192c827af0 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_kms.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_kms.c
@@ -506,6 +506,7 @@ int zynqmp_dpsub_drm_init(struct zynqmp_dpsub *dpsub)
drm->mode_config.min_height = 0;
drm->mode_config.max_width = ZYNQMP_DISP_MAX_WIDTH;
drm->mode_config.max_height = ZYNQMP_DISP_MAX_HEIGHT;
+ drm->mode_config.preferred_depth = 16;
ret = drm_vblank_init(drm, 1);
if (ret)
--
2.34.1
From: Anatoliy Klymenko <anatoliy.klymenko(a)amd.com>
Use RG16 buffer format for fbdev emulation. Fbdev backend is being used
by Mali 400 userspace driver which expects 16 bit RGB pixel color format.
This change should not affect console or other fbdev applications as we
still have plenty of colors left.
Cc: Bill Mills <bill.mills(a)linaro.org>
Cc: Ilias Apalodimas <ilias.apalodimas(a)linaro.org>
Cc: stable(a)vger.kernel.org
Signed-off-by: Anatoliy Klymenko <anatoliy.klymenko(a)amd.com>
Signed-off-by: Mikko Rapeli <mikko.rapeli(a)linaro.org>
---
drivers/gpu/drm/xlnx/zynqmp_kms.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/xlnx/zynqmp_kms.c b/drivers/gpu/drm/xlnx/zynqmp_kms.c
index 2bee0a2275ede..ccc35cacd10cb 100644
--- a/drivers/gpu/drm/xlnx/zynqmp_kms.c
+++ b/drivers/gpu/drm/xlnx/zynqmp_kms.c
@@ -525,7 +525,7 @@ int zynqmp_dpsub_drm_init(struct zynqmp_dpsub *dpsub)
goto err_poll_fini;
/* Initialize fbdev generic emulation. */
- drm_client_setup_with_fourcc(drm, DRM_FORMAT_RGB888);
+ drm_client_setup_with_fourcc(drm, DRM_FORMAT_RGB565);
return 0;
--
2.34.1
If `locked_pages` is zero, the page array must not be allocated:
ceph_process_folio_batch() uses `locked_pages` to decide when to
allocate `pages`, and redundant allocations trigger
ceph_allocate_page_array()'s BUG_ON(), resulting in a worker oops (and
writeback stall) or even a kernel panic. Consequently, the main loop in
ceph_writepages_start() assumes that the lifetime of `pages` is confined
to a single iteration.
The ceph_submit_write() function claims ownership of the page array on
success. But failures only redirty/unlock the pages and fail to free the
array, making the failure case in ceph_submit_write() fatal.
Free the page array in ceph_submit_write()'s error-handling 'if' block
so that the caller's invariant (that the array does not outlive the
iteration) is maintained unconditionally, allowing failures in
ceph_submit_write() to be recoverable as originally intended.
Fixes: 1551ec61dc55 ("ceph: introduce ceph_submit_write() method")
Cc: stable(a)vger.kernel.org
Signed-off-by: Sam Edwards <CFSworks(a)gmail.com>
---
fs/ceph/addr.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 2b722916fb9b..91cc43950162 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -1466,6 +1466,13 @@ int ceph_submit_write(struct address_space *mapping,
unlock_page(page);
}
+ if (ceph_wbc->from_pool) {
+ mempool_free(ceph_wbc->pages, ceph_wb_pagevec_pool);
+ ceph_wbc->from_pool = false;
+ } else
+ kfree(ceph_wbc->pages);
+ ceph_wbc->pages = NULL;
+
ceph_osdc_put_request(req);
return -EIO;
}
--
2.51.2
From: ChiYuan Huang <cy_huang(a)richtek.com>
To make sure LED enter off state after file handle is closed, initiatively
configure LED_MODE to NONE. This can guarantee whatever the previous state
is torch or strobe mode, the final state will be off.
Cc: stable(a)vger.kernel.org
Fixes : 42bd6f59ae90 ("media: Add registration helpers for V4L2 flash sub-devices")
Reported-by: Roger Wang <roger-hy.wang(a)mediatek.com>
Signed-off-by: ChiYuan Huang <cy_huang(a)richtek.com>
---
Hi,
We encounter an issue. When the upper layer camera process is crashed,
if the new process did not reinit the LED, it will keeps the previous
state whatever it's in torch or strobe mode
OS will handle the resource management. So when the process is crashed
or terminated, the 'close' API will be called to release resources.
That's why we add the initiative action to trigger LED off in file
handle close is called.
---
drivers/media/v4l2-core/v4l2-flash-led-class.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-flash-led-class.c b/drivers/media/v4l2-core/v4l2-flash-led-class.c
index 355595a0fefa..347b37f3ef69 100644
--- a/drivers/media/v4l2-core/v4l2-flash-led-class.c
+++ b/drivers/media/v4l2-core/v4l2-flash-led-class.c
@@ -623,6 +623,12 @@ static int v4l2_flash_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
return 0;
if (led_cdev) {
+ /* If file handle is released, make sure LED enter off state */
+ ret = v4l2_ctrl_s_ctrl(v4l2_flash->ctrls[LED_MODE],
+ V4L2_FLASH_LED_MODE_NONE);
+ if (ret)
+ return ret;
+
mutex_lock(&led_cdev->led_access);
if (v4l2_flash->ctrls[STROBE_SOURCE])
--
2.34.1