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[Intel-SIG] new CPU topology series - 1/4: x86/cpu: Rework the topology evaluation - part1#8

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[Intel-SIG] new CPU topology series - 1/4: x86/cpu: Rework the topology evaluation - part1#8
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CPU topology series:
There are totally 5 series for this new cpu topology.
1st has been in 6.6, 2nd, 3rd, 4th, 5th series will be backported to 6.6. This PR is 5th patch series.

patch series 1: [patch V3 00/60] x86/apic: Decrapification and static calls
https://lore.kernel.org/all/20230801103042.936020332@linutronix.de/
Patches are merged in 6.6-rc1
Patch series 2: [patch V4 00/41] x86/cpu: Rework the topology evaluation
https://lore.kernel.org/all/20230814085006.593997112@linutronix.de/
Patch 1-22 merged in 6.7-rc1
Patch series 3: [patch V6 00/19] x86/cpu: Rework topology evaluation
https://lore.kernel.org/all/20240212153109.330805450@linutronix.de/
Patch series 4: [patch V3 00/22] x86/topology: More cleanups and preparatory work
https://lore.kernel.org/all/20240212154529.402604963@linutronix.de/
Patch series 5: [patch 00/30] x86/apic: Rework APIC registration
https://lore.kernel.org/all/20240213205415.307029033@linutronix.de/
Patches are merged in this merge window and should be included in 6.9-rc1.

Testing:
Intel platform
EMR/SRFSP/GNRSP/CWF/DMR simics testing - PASS

Testing Process:
git clone https://github.com/intel/lkvs
cd lkvs/BM

testcase-1:
#./runtests -c cpu_topology.sh -t numa_nodes_compare
[RESULT][cpu_topology.sh] [PASS] [0] [0.163s]
testcase-2:
./runtests -c cpu_topology.sh -t verify_thread_per_core
[RESULT][cpu_topology.sh] [PASS] [0] [0.158s]
testcase-3:
#./runtests -c cpu_topology.sh -t verify_cores_per_socket
[RESULT][cpu_topology.sh] [PASS] [0] [0.158s]
testcase-4:
#./runtests -c cpu_topology.sh -t verify_socket_num
[RESULT][cpu_topology.sh] [PASS] [0] [0.155s]
testcase-5:
#./runtests -c cpu_topology.sh -t verify_level_type
[RESULT][cpu_topology.sh] [PASS] [0] [0.158s]

package dependency: cpuid tools (used by test 1-5)

KAGA-KOKO and others added 16 commits December 15, 2025 22:12
commit 94f0b39 upstream.

Use the provided topology helper function instead of fiddling in cpu_data.

Intel-SIG: commit 94f0b39 hwmon: (fam15h_power) Use topology_core_id().
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.506988471@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit e952563 upstream.

Rename it to core_id and stick it to the other ID fields.

No functional change.

Intel-SIG: commit e952563 x86/cpu: Move cpu_core_id into topology info.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.566519388@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit e3c0c5d upstream.

No functional change.

Intel-SIG: commit e3c0c5d x86/cpu: Move cu_id into topology info.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.628405546@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 594957d upstream.

cpuinfo_x86::x86_coreid_bits is only used by the AMD numa topology code. No
point in evaluating it on non AMD systems.

No functional change.

Intel-SIG: commit 594957d x86/cpu: Remove pointless evaluation of x86_coreid_bits.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.687588373@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 22dc963 upstream.

Yet another topology related data pair. Rename logical_proc_id to
logical_pkg_id so it fits the common naming conventions.

No functional change.

Intel-SIG: commit 22dc963 x86/cpu: Move logical package and die IDs into topology info.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.745139505@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 6e29032 upstream.

The topology IDs which identify the LLC and L2 domains clearly belong to
the per CPU topology information.

Move them into cpuinfo_x86::cpuinfo_topo and get rid of the extra per CPU
data and the related exports.

This also paves the way to do proper topology evaluation during early boot
because it removes the only per CPU dependency for that.

No functional change.

Intel-SIG: commit 6e29032 x86/cpu: Move cpu_l[l2]c_id into topology info.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.803864641@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 9ff4275 upstream.

APIC ID checks compare with BAD_APICID all over the place, but some
initializers and some code which fiddles with global data structure use
-1[U] instead. That simply cannot work at all.

Fix it up and use BAD_APICID consistently all over the place.

Intel-SIG: commit 9ff4275 x86/apic: Use BAD_APICID consistently.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.862835121@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 4705243 upstream.

APIC IDs are used with random data types u16, u32, int, unsigned int,
unsigned long.

Make it all consistently use u32 because that reflects the hardware
register width and fixup the most obvious usage sites of that.

The APIC callbacks will be addressed separately.

Intel-SIG: commit 4705243 x86/apic: Use u32 for APIC IDs in global data.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.922905727@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 5d376b8 upstream.

APIC IDs are used with random data types u16, u32, int, unsigned int,
unsigned long.

Make it all consistently use u32 because that reflects the hardware
register width and move the default implementation to local.h as there are
no users outside the apic directory.

Intel-SIG: commit 5d376b8 x86/apic: Use u32 for check_apicid_used().
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085112.981956102@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 8aa2a41 upstream.

APIC IDs are used with random data types u16, u32, int, unsigned int,
unsigned long.

Make it all consistently use u32 because that reflects the hardware
register width and fixup a few related usage sites for consistency sake.

Intel-SIG: commit 8aa2a41 x86/apic: Use u32 for cpu_present_to_apicid().
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085113.054064391@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 01ccf9b upstream.

APIC IDs are used with random data types u16, u32, int, unsigned int,
unsigned long.

Make it all consistently use u32 because that reflects the hardware
register width even if that callback going to be removed soonish.

Intel-SIG: commit 01ccf9b x86/apic: Use u32 for phys_pkg_id().
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085113.113097126@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 59f7928 upstream.

APIC IDs are used with random data types u16, u32, int, unsigned int,
unsigned long.

Make it all consistently use u32 because that reflects the hardware
register width.

Intel-SIG: commit 59f7928 x86/apic: Use u32 for [gs]et_apic_id().
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085113.172569282@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 92fe9bb upstream.

The data type for APIC IDs was standardized to 'u32' in the
following recent commit:

   db4a408 ("x86/apic: Use u32 for wakeup_secondary_cpu[_64]()")

Which changed the function arguments type signature of the
apic->wakeup_secondary_cpu() APIC driver function.

Propagate this to hv_snp_boot_ap() as well, which also addresses a
'assignment from incompatible pointer type' build warning that triggers
under the -Werror=incompatible-pointer-types GCC warning.

Fixes: db4a408 ("x86/apic: Use u32 for wakeup_secondary_cpu[_64]()")
Intel-SIG: commit 92fe9bb x86/apic, x86/hyperv: Use u32 in hv_snp_boot_ap() too.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230814085113.233274223@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit db4a408 upstream.

APIC IDs are used with random data types u16, u32, int, unsigned int,
unsigned long.

Make it all consistently use u32 because that reflects the hardware
register width.

Intel-SIG: commit db4a408 x86/apic: Use u32 for wakeup_secondary_cpu[_64]().
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Reviewed-by: Arjan van de Ven <arjan@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085113.233274223@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 90781f0 upstream.

Per CPU cpuinfo is used to persist the logical package and die IDs. That's
really not the right place simply because cpuinfo is subject to be
reinitialized when a CPU goes through an offline/online cycle.

This works by chance today, but that's far from correct and neither obvious
nor documented.

Add a per cpu datastructure which persists those logical IDs, which allows
to cleanup the CPUID evaluation code.

This is a temporary workaround until the larger topology management is in
place, which makes all of this logical management mechanics obsolete.

Intel-SIG: commit 90781f0 x86/cpu/topology: Cure the abuse of cpuinfo for persisting logical ids.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085113.292947071@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
commit 48525fd upstream.

Provide debug files which dump the topology related information of
cpuinfo_x86. This is useful to validate the upcoming conversion of the
topology evaluation for correctness or bug compatibility.

Intel-SIG: commit 48525fd x86/cpu: Provide debug interface.
x86/cpu: Rework the topology evaluation - part1

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juergen Gross <jgross@suse.com>
Tested-by: Sohil Mehta <sohil.mehta@intel.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20230814085113.353191313@linutronix.de
[ Quanxian Wang: amend commit log ]
Signed-off-by: Quanxian Wang <quanxian.wang@intel.com>
x56Jason pushed a commit that referenced this pull request Mar 3, 2026
commit 05703271c3cdcc0f2a8cf6ebdc45892b8ca83520 upstream.

Before disabling SR-IOV via config space accesses to the parent PF,
sriov_disable() first removes the PCI devices representing the VFs.

Since commit 9d16947 ("PCI: Add global pci_lock_rescan_remove()")
such removal operations are serialized against concurrent remove and
rescan using the pci_rescan_remove_lock. No such locking was ever added
in sriov_disable() however. In particular when commit 18f9e9d
("PCI/IOV: Factor out sriov_add_vfs()") factored out the PCI device
removal into sriov_del_vfs() there was still no locking around the
pci_iov_remove_virtfn() calls.

On s390 the lack of serialization in sriov_disable() may cause double
remove and list corruption with the below (amended) trace being observed:

  PSW:  0704c00180000000 0000000c914e4b38 (klist_put+56)
  GPRS: 000003800313fb48 0000000000000000 0000000100000001 0000000000000001
	00000000f9b520a8 0000000000000000 0000000000002fbd 00000000f4cc9480
	0000000000000001 0000000000000000 0000000000000000 0000000180692828
	00000000818e8000 000003800313fe2c 000003800313fb20 000003800313fad8
  #0 [3800313fb20] device_del at c9158ad5c
  #1 [3800313fb88] pci_remove_bus_device at c915105ba
  #2 [3800313fbd0] pci_iov_remove_virtfn at c9152f198
  #3 [3800313fc28] zpci_iov_remove_virtfn at c90fb67c0
  #4 [3800313fc60] zpci_bus_remove_device at c90fb6104
  #5 [3800313fca0] __zpci_event_availability at c90fb3dca
  #6 [3800313fd08] chsc_process_sei_nt0 at c918fe4a2
  #7 [3800313fd60] crw_collect_info at c91905822
  #8 [3800313fe10] kthread at c90feb390
  #9 [3800313fe68] __ret_from_fork at c90f6aa64
  openvelinux#10 [3800313fe98] ret_from_fork at c9194f3f2.

This is because in addition to sriov_disable() removing the VFs, the
platform also generates hot-unplug events for the VFs. This being the
reverse operation to the hotplug events generated by sriov_enable() and
handled via pdev->no_vf_scan. And while the event processing takes
pci_rescan_remove_lock and checks whether the struct pci_dev still exists,
the lack of synchronization makes this checking racy.

Other races may also be possible of course though given that this lack of
locking persisted so long observable races seem very rare. Even on s390 the
list corruption was only observed with certain devices since the platform
events are only triggered by config accesses after the removal, so as long
as the removal finished synchronously they would not race. Either way the
locking is missing so fix this by adding it to the sriov_del_vfs() helper.

Just like PCI rescan-remove, locking is also missing in sriov_add_vfs()
including for the error case where pci_stop_and_remove_bus_device() is
called without the PCI rescan-remove lock being held. Even in the non-error
case, adding new PCI devices and buses should be serialized via the PCI
rescan-remove lock. Add the necessary locking.

Fixes: 18f9e9d ("PCI/IOV: Factor out sriov_add_vfs()")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Reviewed-by: Farhan Ali <alifm@linux.ibm.com>
Reviewed-by: Julian Ruess <julianr@linux.ibm.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250826-pci_fix_sriov_disable-v1-1-2d0bc938f2a3@linux.ibm.com
Signed-off-by: Jinhui Guo <guojinhui.liam@bytedance.com>
x56Jason pushed a commit that referenced this pull request Mar 3, 2026
[ Upstream commit ffbf4fb ]

When CONFIG_DEBUG_BUGVERBOSE=n, we fail to add necessary padding bytes
to bug_table entries, and as a result the last entry in a bug table will
be ignored, potentially leading to an unexpected panic(). All prior
entries in the table will be handled correctly.

The arm64 ABI requires that struct fields of up to 8 bytes are
naturally-aligned, with padding added within a struct such that struct
are suitably aligned within arrays.

When CONFIG_DEBUG_BUGVERPOSE=y, the layout of a bug_entry is:

	struct bug_entry {
		signed int      bug_addr_disp;	// 4 bytes
		signed int      file_disp;	// 4 bytes
		unsigned short  line;		// 2 bytes
		unsigned short  flags;		// 2 bytes
	}

... with 12 bytes total, requiring 4-byte alignment.

When CONFIG_DEBUG_BUGVERBOSE=n, the layout of a bug_entry is:

	struct bug_entry {
		signed int      bug_addr_disp;	// 4 bytes
		unsigned short  flags;		// 2 bytes
		< implicit padding >		// 2 bytes
	}

... with 8 bytes total, with 6 bytes of data and 2 bytes of trailing
padding, requiring 4-byte alginment.

When we create a bug_entry in assembly, we align the start of the entry
to 4 bytes, which implicitly handles padding for any prior entries.
However, we do not align the end of the entry, and so when
CONFIG_DEBUG_BUGVERBOSE=n, the final entry lacks the trailing padding
bytes.

For the main kernel image this is not a problem as find_bug() doesn't
depend on the trailing padding bytes when searching for entries:

	for (bug = __start___bug_table; bug < __stop___bug_table; ++bug)
		if (bugaddr == bug_addr(bug))
			return bug;

However for modules, module_bug_finalize() depends on the trailing
bytes when calculating the number of entries:

	mod->num_bugs = sechdrs[i].sh_size / sizeof(struct bug_entry);

... and as the last bug_entry lacks the necessary padding bytes, this entry
will not be counted, e.g. in the case of a single entry:

	sechdrs[i].sh_size == 6
	sizeof(struct bug_entry) == 8;

	sechdrs[i].sh_size / sizeof(struct bug_entry) == 0;

Consequently module_find_bug() will miss the last bug_entry when it does:

	for (i = 0; i < mod->num_bugs; ++i, ++bug)
		if (bugaddr == bug_addr(bug))
			goto out;

... which can lead to a kenrel panic due to an unhandled bug.

This can be demonstrated with the following module:

	static int __init buginit(void)
	{
		WARN(1, "hello
");
		return 0;
	}

	static void __exit bugexit(void)
	{
	}

	module_init(buginit);
	module_exit(bugexit);
	MODULE_LICENSE("GPL");

... which will trigger a kernel panic when loaded:

	------------[ cut here ]------------
	hello
	Unexpected kernel BRK exception at EL1
	Internal error: BRK handler: 00000000f2000800 [#1] PREEMPT SMP
	Modules linked in: hello(O+)
	CPU: 0 PID: 50 Comm: insmod Tainted: G           O       6.9.1 #8
	Hardware name: linux,dummy-virt (DT)
	pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
	pc : buginit+0x18/0x1000 [hello]
	lr : buginit+0x18/0x1000 [hello]
	sp : ffff800080533ae0
	x29: ffff800080533ae0 x28: 0000000000000000 x27: 0000000000000000
	x26: ffffaba8c4e70510 x25: ffff800080533c30 x24: ffffaba8c4a28a58
	x23: 0000000000000000 x22: 0000000000000000 x21: ffff3947c0eab3c0
	x20: ffffaba8c4e3f000 x19: ffffaba846464000 x18: 0000000000000006
	x17: 0000000000000000 x16: ffffaba8c2492834 x15: 0720072007200720
	x14: 0720072007200720 x13: ffffaba8c49b27c8 x12: 0000000000000312
	x11: 0000000000000106 x10: ffffaba8c4a0a7c8 x9 : ffffaba8c49b27c8
	x8 : 00000000ffffefff x7 : ffffaba8c4a0a7c8 x6 : 80000000fffff000
	x5 : 0000000000000107 x4 : 0000000000000000 x3 : 0000000000000000
	x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff3947c0eab3c0
	Call trace:
	 buginit+0x18/0x1000 [hello]
	 do_one_initcall+0x80/0x1c8
	 do_init_module+0x60/0x218
	 load_module+0x1ba4/0x1d70
	 __do_sys_init_module+0x198/0x1d0
	 __arm64_sys_init_module+0x1c/0x28
	 invoke_syscall+0x48/0x114
	 el0_svc_common.constprop.0+0x40/0xe0
	 do_el0_svc+0x1c/0x28
	 el0_svc+0x34/0xd8
	 el0t_64_sync_handler+0x120/0x12c
	 el0t_64_sync+0x190/0x194
	Code: d0ffffe0 910003fd 91000000 9400000b (d4210000)
	---[ end trace 0000000000000000 ]---
	Kernel panic - not syncing: BRK handler: Fatal exception

Fix this by always aligning the end of a bug_entry to 4 bytes, which is
correct regardless of CONFIG_DEBUG_BUGVERBOSE.

Fixes: 9fb7410 ("arm64/BUG: Use BRK instruction for generic BUG traps")

Signed-off-by: Yuanbin Xie <xieyuanbin1@huawei.com>
Signed-off-by: Jiangfeng Xiao <xiaojiangfeng@huawei.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/1716212077-43826-1-git-send-email-xiaojiangfeng@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Ashish Bijlani <ashish.bijlani@bytedance.com>
x56Jason pushed a commit that referenced this pull request Mar 3, 2026
…le_direct_reclaim()

commit 6aaced5abd32e2a57cd94fd64f824514d0361da8 upstream.

The task sometimes continues looping in throttle_direct_reclaim() because
allow_direct_reclaim(pgdat) keeps returning false.

 #0 [ffff80002cb6f8d0] __switch_to at ffff8000080095ac
 #1 [ffff80002cb6f900] __schedule at ffff800008abbd1c
 #2 [ffff80002cb6f990] schedule at ffff800008abc50c
 #3 [ffff80002cb6f9b0] throttle_direct_reclaim at ffff800008273550
 #4 [ffff80002cb6fa20] try_to_free_pages at ffff800008277b68
 #5 [ffff80002cb6fae0] __alloc_pages_nodemask at ffff8000082c4660
 #6 [ffff80002cb6fc50] alloc_pages_vma at ffff8000082e4a98
 #7 [ffff80002cb6fca0] do_anonymous_page at ffff80000829f5a8
 #8 [ffff80002cb6fce0] __handle_mm_fault at ffff8000082a5974
 #9 [ffff80002cb6fd90] handle_mm_fault at ffff8000082a5bd4

At this point, the pgdat contains the following two zones:

        NODE: 4  ZONE: 0  ADDR: ffff00817fffe540  NAME: "DMA32"
          SIZE: 20480  MIN/LOW/HIGH: 11/28/45
          VM_STAT:
                NR_FREE_PAGES: 359
        NR_ZONE_INACTIVE_ANON: 18813
          NR_ZONE_ACTIVE_ANON: 0
        NR_ZONE_INACTIVE_FILE: 50
          NR_ZONE_ACTIVE_FILE: 0
          NR_ZONE_UNEVICTABLE: 0
        NR_ZONE_WRITE_PENDING: 0
                     NR_MLOCK: 0
                    NR_BOUNCE: 0
                   NR_ZSPAGES: 0
            NR_FREE_CMA_PAGES: 0

        NODE: 4  ZONE: 1  ADDR: ffff00817fffec00  NAME: "Normal"
          SIZE: 8454144  PRESENT: 98304  MIN/LOW/HIGH: 68/166/264
          VM_STAT:
                NR_FREE_PAGES: 146
        NR_ZONE_INACTIVE_ANON: 94668
          NR_ZONE_ACTIVE_ANON: 3
        NR_ZONE_INACTIVE_FILE: 735
          NR_ZONE_ACTIVE_FILE: 78
          NR_ZONE_UNEVICTABLE: 0
        NR_ZONE_WRITE_PENDING: 0
                     NR_MLOCK: 0
                    NR_BOUNCE: 0
                   NR_ZSPAGES: 0
            NR_FREE_CMA_PAGES: 0

In allow_direct_reclaim(), while processing ZONE_DMA32, the sum of
inactive/active file-backed pages calculated in zone_reclaimable_pages()
based on the result of zone_page_state_snapshot() is zero.

Additionally, since this system lacks swap, the calculation of inactive/
active anonymous pages is skipped.

        crash> p nr_swap_pages
        nr_swap_pages = $1937 = {
          counter = 0
        }

As a result, ZONE_DMA32 is deemed unreclaimable and skipped, moving on to
the processing of the next zone, ZONE_NORMAL, despite ZONE_DMA32 having
free pages significantly exceeding the high watermark.

The problem is that the pgdat->kswapd_failures hasn't been incremented.

        crash> px ((struct pglist_data *) 0xffff00817fffe540)->kswapd_failures
        $1935 = 0x0

This is because the node deemed balanced.  The node balancing logic in
balance_pgdat() evaluates all zones collectively.  If one or more zones
(e.g., ZONE_DMA32) have enough free pages to meet their watermarks, the
entire node is deemed balanced.  This causes balance_pgdat() to exit early
before incrementing the kswapd_failures, as it considers the overall
memory state acceptable, even though some zones (like ZONE_NORMAL) remain
under significant pressure.

The patch ensures that zone_reclaimable_pages() includes free pages
(NR_FREE_PAGES) in its calculation when no other reclaimable pages are
available (e.g., file-backed or anonymous pages).  This change prevents
zones like ZONE_DMA32, which have sufficient free pages, from being
mistakenly deemed unreclaimable.  By doing so, the patch ensures proper
node balancing, avoids masking pressure on other zones like ZONE_NORMAL,
and prevents infinite loops in throttle_direct_reclaim() caused by
allow_direct_reclaim(pgdat) repeatedly returning false.

The kernel hangs due to a task stuck in throttle_direct_reclaim(), caused
by a node being incorrectly deemed balanced despite pressure in certain
zones, such as ZONE_NORMAL.  This issue arises from
zone_reclaimable_pages() returning 0 for zones without reclaimable file-
backed or anonymous pages, causing zones like ZONE_DMA32 with sufficient
free pages to be skipped.

The lack of swap or reclaimable pages results in ZONE_DMA32 being ignored
during reclaim, masking pressure in other zones.  Consequently,
pgdat->kswapd_failures remains 0 in balance_pgdat(), preventing fallback
mechanisms in allow_direct_reclaim() from being triggered, leading to an
infinite loop in throttle_direct_reclaim().

This patch modifies zone_reclaimable_pages() to account for free pages
(NR_FREE_PAGES) when no other reclaimable pages exist.  This ensures zones
with sufficient free pages are not skipped, enabling proper balancing and
reclaim behavior.

[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20241130164346.436469-1-snishika@redhat.com
Link: https://lkml.kernel.org/r/20241130161236.433747-2-snishika@redhat.com
Fixes: 5a1c84b ("mm: remove reclaim and compaction retry approximations")
Signed-off-by: Seiji Nishikawa <snishika@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ashish Bijlani <ashish.bijlani@bytedance.com>
x56Jason pushed a commit that referenced this pull request Mar 3, 2026
commit 32ca245464e1479bfea8592b9db227fdc1641705 upstream.

Jann Horn reported a use-after-free in unix_stream_read_generic().

The following sequences reproduce the issue:

  $ python3
  from socket import *
  s1, s2 = socketpair(AF_UNIX, SOCK_STREAM)
  s1.send(b'x', MSG_OOB)
  s2.recv(1, MSG_OOB)     # leave a consumed OOB skb
  s1.send(b'y', MSG_OOB)
  s2.recv(1, MSG_OOB)     # leave a consumed OOB skb
  s1.send(b'z', MSG_OOB)
  s2.recv(1)              # recv 'z' illegally
  s2.recv(1, MSG_OOB)     # access 'z' skb (use-after-free)

Even though a user reads OOB data, the skb holding the data stays on
the recv queue to mark the OOB boundary and break the next recv().

After the last send() in the scenario above, the sk2's recv queue has
2 leading consumed OOB skbs and 1 real OOB skb.

Then, the following happens during the next recv() without MSG_OOB

  1. unix_stream_read_generic() peeks the first consumed OOB skb
  2. manage_oob() returns the next consumed OOB skb
  3. unix_stream_read_generic() fetches the next not-yet-consumed OOB skb
  4. unix_stream_read_generic() reads and frees the OOB skb

, and the last recv(MSG_OOB) triggers KASAN splat.

The 3. above occurs because of the SO_PEEK_OFF code, which does not
expect unix_skb_len(skb) to be 0, but this is true for such consumed
OOB skbs.

  while (skip >= unix_skb_len(skb)) {
    skip -= unix_skb_len(skb);
    skb = skb_peek_next(skb, &sk->sk_receive_queue);
    ...
  }

In addition to this use-after-free, there is another issue that
ioctl(SIOCATMARK) does not function properly with consecutive consumed
OOB skbs.

So, nothing good comes out of such a situation.

Instead of complicating manage_oob(), ioctl() handling, and the next
ECONNRESET fix by introducing a loop for consecutive consumed OOB skbs,
let's not leave such consecutive OOB unnecessarily.

Now, while receiving an OOB skb in unix_stream_recv_urg(), if its
previous skb is a consumed OOB skb, it is freed.

[0]:
BUG: KASAN: slab-use-after-free in unix_stream_read_actor (net/unix/af_unix.c:3027)
Read of size 4 at addr ffff888106ef2904 by task python3/315

CPU: 2 UID: 0 PID: 315 Comm: python3 Not tainted 6.16.0-rc1-00407-gec315832f6f9 #8 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl (lib/dump_stack.c:122)
 print_report (mm/kasan/report.c:409 mm/kasan/report.c:521)
 kasan_report (mm/kasan/report.c:636)
 unix_stream_read_actor (net/unix/af_unix.c:3027)
 unix_stream_read_generic (net/unix/af_unix.c:2708 net/unix/af_unix.c:2847)
 unix_stream_recvmsg (net/unix/af_unix.c:3048)
 sock_recvmsg (net/socket.c:1063 (discriminator 20) net/socket.c:1085 (discriminator 20))
 __sys_recvfrom (net/socket.c:2278)
 __x64_sys_recvfrom (net/socket.c:2291 (discriminator 1) net/socket.c:2287 (discriminator 1) net/socket.c:2287 (discriminator 1))
 do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
RIP: 0033:0x7f8911fcea06
Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08
RSP: 002b:00007fffdb0dccb0 EFLAGS: 00000202 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 00007fffdb0dcdc8 RCX: 00007f8911fcea06
RDX: 0000000000000001 RSI: 00007f8911a5e060 RDI: 0000000000000006
RBP: 00007fffdb0dccd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000202 R12: 00007f89119a7d20
R13: ffffffffc4653600 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Allocated by task 315:
 kasan_save_stack (mm/kasan/common.c:48)
 kasan_save_track (mm/kasan/common.c:60 (discriminator 1) mm/kasan/common.c:69 (discriminator 1))
 __kasan_slab_alloc (mm/kasan/common.c:348)
 kmem_cache_alloc_node_noprof (./include/linux/kasan.h:250 mm/slub.c:4148 mm/slub.c:4197 mm/slub.c:4249)
 __alloc_skb (net/core/skbuff.c:660 (discriminator 4))
 alloc_skb_with_frags (./include/linux/skbuff.h:1336 net/core/skbuff.c:6668)
 sock_alloc_send_pskb (net/core/sock.c:2993)
 unix_stream_sendmsg (./include/net/sock.h:1847 net/unix/af_unix.c:2256 net/unix/af_unix.c:2418)
 __sys_sendto (net/socket.c:712 (discriminator 20) net/socket.c:727 (discriminator 20) net/socket.c:2226 (discriminator 20))
 __x64_sys_sendto (net/socket.c:2233 (discriminator 1) net/socket.c:2229 (discriminator 1) net/socket.c:2229 (discriminator 1))
 do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

Freed by task 315:
 kasan_save_stack (mm/kasan/common.c:48)
 kasan_save_track (mm/kasan/common.c:60 (discriminator 1) mm/kasan/common.c:69 (discriminator 1))
 kasan_save_free_info (mm/kasan/generic.c:579 (discriminator 1))
 __kasan_slab_free (mm/kasan/common.c:271)
 kmem_cache_free (mm/slub.c:4643 (discriminator 3) mm/slub.c:4745 (discriminator 3))
 unix_stream_read_generic (net/unix/af_unix.c:3010)
 unix_stream_recvmsg (net/unix/af_unix.c:3048)
 sock_recvmsg (net/socket.c:1063 (discriminator 20) net/socket.c:1085 (discriminator 20))
 __sys_recvfrom (net/socket.c:2278)
 __x64_sys_recvfrom (net/socket.c:2291 (discriminator 1) net/socket.c:2287 (discriminator 1) net/socket.c:2287 (discriminator 1))
 do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
 entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)

The buggy address belongs to the object at ffff888106ef28c0
 which belongs to the cache skbuff_head_cache of size 224
The buggy address is located 68 bytes inside of
 freed 224-byte region [ffff888106ef28c0, ffff888106ef29a0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888106ef3cc0 pfn:0x106ef2
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x200000000000040(head|node=0|zone=2)
page_type: f5(slab)
raw: 0200000000000040 ffff8881001d28c0 ffffea000422fe00 0000000000000004
raw: ffff888106ef3cc0 0000000080190010 00000000f5000000 0000000000000000
head: 0200000000000040 ffff8881001d28c0 ffffea000422fe00 0000000000000004
head: ffff888106ef3cc0 0000000080190010 00000000f5000000 0000000000000000
head: 0200000000000001 ffffea00041bbc81 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888106ef2800: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
 ffff888106ef2880: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
>ffff888106ef2900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888106ef2980: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888106ef2a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

Fixes: 314001f ("af_unix: Add OOB support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Jann Horn <jannh@google.com>
Link: https://patch.msgid.link/20250619041457.1132791-2-kuni1840@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[Lee: Shifted hunk inside the if() statement and surrounded the else with {}'s)
Signed-off-by: Lee Jones <lee@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 523edfed4f68b7794d85b9ac828c5f8f4442e4c5)
Signed-off-by: Rui Zhang <zhangrui.rod@bytedance.com>
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