Dear Maintainer,

Afeter kernel upgrade to 7.2.11+deb14-amd64 the hostapd stopped working. When debuging the problem, I fuound the reason is the Mediatek Wireless device failing to set in the AP mode. THe debug information from hostapd below.
After reboot to 7.2.9+deb14-amd64 kernel, the problem went off immediately so the changes between these 2 versions must have lead to the problem.

ctrl_interface_group=0
eapol_version=1
Line 761: Obsolete peerkey parameter ignored
nl80211: TDLS supported
nl80211: TDLS external setup
nl80211: Supported cipher 00-0f-ac:1
nl80211: Supported cipher 00-0f-ac:5
nl80211: Supported cipher 00-0f-ac:2
nl80211: Supported cipher 00-0f-ac:4
nl80211: Supported cipher 00-0f-ac:10
nl80211: Supported cipher 00-0f-ac:8
nl80211: Supported cipher 00-0f-ac:9
nl80211: Supported cipher 00-0f-ac:6
nl80211: Supported cipher 00-0f-ac:13
nl80211: Supported cipher 00-0f-ac:11
nl80211: Supported cipher 00-0f-ac:12
nl80211: Using driver-based off-channel TX
nl80211: Driver-advertised extended capabilities (default) - hexdump(len=8): 04 00 00 00 00 00 00 40
nl80211: Driver-advertised extended capabilities mask (default) - hexdump(len=8): 04 00 00 00 00 00 00 40
nl80211: Use separate P2P group interface (driver advertised support)
nl80211: key_mgmt=0x1ff0f enc=0xfef auth=0x7 flags=0x4000511db1bfae0 rrm_flags=0x10 probe_resp_offloads=0x0 max_stations=0 max_remain_on_chan=5000 max_scan_ssids=4
nl80211: interface wlan_24 in phy phy1
nl80211: Set mode ifindex 4 iftype 3 (AP)
nl80211: Setup AP(wlan_24) - device_ap_sme=0 use_monitor=0
nl80211: Subscribe to mgmt frames with AP handle 0x561aa3d1abf0
nl80211: Register frame type=0xb0 (WLAN_FC_STYPE_AUTH) nl_handle=0x561aa3d1abf0 match= multicast=0
nl80211: Register frame type=0x0 (WLAN_FC_STYPE_ASSOC_REQ) nl_handle=0x561aa3d1abf0 match= multicast=0
nl80211: Register frame type=0x20 (WLAN_FC_STYPE_REASSOC_REQ) nl_handle=0x561aa3d1abf0 match= multicast=0
nl80211: Register frame type=0xa0 (WLAN_FC_STYPE_DISASSOC) nl_handle=0x561aa3d1abf0 match= multicast=0
nl80211: Register frame type=0xc0 (WLAN_FC_STYPE_DEAUTH) nl_handle=0x561aa3d1abf0 match= multicast=0
nl80211: Register frame type=0x40 (WLAN_FC_STYPE_PROBE_REQ) nl_handle=0x561aa3d1abf0 match= multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=04 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=0501 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=0503 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=0504 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=06 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=08 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=09 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=0a multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=11 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=12 multicast=0
nl80211: Register frame type=0xd0 (WLAN_FC_STYPE_ACTION) nl_handle=0x561aa3d1abf0 match=7f multicast=0
rfkill: initial event: idx=0 type=1 op=0 soft=0 hard=0
Could not set interface wlan_24 flags (UP): Message too long
nl80211: Could not set interface 'wlan_24' UP
nl80211: deinit ifname=wlan_24 disabled_11b_rates=0
nl80211: Remove monitor interface: refcount=0
nl80211: Remove beacon (ifindex=4)

Hi Michal,

Sorry for that. Could you please bisect the changes between 7.2.9 and
7.2.11 upstream with the following procedure please, so we can
identify the problemtic change?

    git clone --single-branch -b linux-7.2.y https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git
    cd linux-stable
    git checkout v7.2.9
    cp /boot/config-$(uname -r) .config
    yes '' | make localmodconfig
    make savedefconfig
    mv defconfig arch/x86/configs/my_defconfig

    # test 7.2.9 to ensure this is "good"
    make my_defconfig
    make -j $(nproc) bindeb-pkg
    ... install the resulting .deb package and confirm problem does not exist

    # test 7.2.11 to ensure this is "bad"
    git checkout v7.2.11
    make my_defconfig
    make -j $(nproc) bindeb-pkg
    ... install the resulting .deb package and confirm problem exists

With that confirmed, the bisection can start:

    git bisect start
    git bisect good v7.2.9
    git bisect bad v7.2.11

In each bisection step git checks out a state between the oldest
known-bad and the newest known-good commit. In each step test using:

    make my_defconfig
    make -j $(nproc) bindeb-pkg
    ... install, try to verify if problem exists

and if the problem is hit run:

    git bisect bad

and if the problem doesn't trigger run:

    git bisect good

. Please pay attention to always select the just built kernel for
booting, it won't always be the default kernel picked up by grub.

Iterate until git announces to have identified the first bad commit.

Then provide the output of

    git bisect log

In the course of the bisection you might have to uninstall previous
kernels again to not exhaust the disk space in /boot. Also in the end
uninstall all self-built kernels again.

Regards,
Salvatore