If an interrupt occurs in queued_spin_lock_slowpath() after we increment
qnodesp->count and before node->lock is initialized, another CPU might
see stale lock values in get_tail_qnode(). If the stale lock value happens
to match the lock on that CPU, then we write to the "next" pointer of
the wrong qnode. This causes a deadlock as the former CPU, once it becomes
the head of the MCS queue, will spin indefinitely until it's "next" pointer
is set by its successor in the queue.
Running stress-ng on a 16 core (16EC/16VP) shared LPAR, results in
occasional lockups similar to the following:
$ stress-ng --all 128 --vm-bytes 80% --aggressive \
--maximize --oomable --verify --syslog \
--metrics --times --timeout 5m
watchdog: CPU 15 Hard LOCKUP
......
NIP [c0000000000b78f4] queued_spin_lock_slowpath+0x1184/0x1490
LR [c000000001037c5c] _raw_spin_lock+0x6c/0x90
Call Trace:
0xc000002cfffa3bf0 (unreliable)
_raw_spin_lock+0x6c/0x90
raw_spin_rq_lock_nested.part.135+0x4c/0xd0
sched_ttwu_pending+0x60/0x1f0
__flush_smp_call_function_queue+0x1dc/0x670
smp_ipi_demux_relaxed+0xa4/0x100
xive_muxed_ipi_action+0x20/0x40
__handle_irq_event_percpu+0x80/0x240
handle_irq_event_percpu+0x2c/0x80
handle_percpu_irq+0x84/0xd0
generic_handle_irq+0x54/0x80
__do_irq+0xac/0x210
__do_IRQ+0x74/0xd0
0x0
do_IRQ+0x8c/0x170
hardware_interrupt_common_virt+0x29c/0x2a0
--- interrupt: 500 at queued_spin_lock_slowpath+0x4b8/0x1490
......
NIP [c0000000000b6c28] queued_spin_lock_slowpath+0x4b8/0x1490
LR [c000000001037c5c] _raw_spin_lock+0x6c/0x90
--- interrupt: 500
0xc0000029c1a41d00 (unreliable)
_raw_spin_lock+0x6c/0x90
futex_wake+0x100/0x260
do_futex+0x21c/0x2a0
sys_futex+0x98/0x270
system_call_exception+0x14c/0x2f0
system_call_vectored_common+0x15c/0x2ec
The following code flow illustrates how the deadlock occurs.
For the sake of brevity, assume that both locks (A and B) are
contended and we call the queued_spin_lock_slowpath() function.
CPU0 CPU1
---- ----
spin_lock_irqsave(A) |
spin_unlock_irqrestore(A) |
spin_lock(B) |
| |
▼ |
id = qnodesp->count++; |
(Note that nodes[0].lock == A) |
| |
▼ |
Interrupt |
(happens before "nodes[0].lock = B") |
| |
▼ |
spin_lock_irqsave(A) |
| |
▼ |
id = qnodesp->count++ |
nodes[1].lock = A |
| |
▼ |
Tail of MCS queue |
| spin_lock_irqsave(A)
▼ |
Head of MCS queue ▼
| CPU0 is previous tail
▼ |
Spin indefinitely ▼
(until "nodes[1].next != NULL") prev = get_tail_qnode(A, CPU0)
|
▼
prev == &qnodes[CPU0].nodes[0]
(as qnodes[CPU0].nodes[0].lock == A)
|
▼
WRITE_ONCE(prev->next, node)
|
▼
Spin indefinitely
(until nodes[0].locked == 1)
Thanks to Saket Kumar Bhaskar for help with recreating the issue
Fixes: 84990b169557 ("powerpc/qspinlock: add mcs queueing for contended waiters")
Cc: stable@vger.kernel.org # v6.2+
Reported-by: Geetika Moolchandani <geetika@linux.ibm.com>
Reported-by: Vaishnavi Bhat <vaish123@in.ibm.com>
Reported-by: Jijo Varghese <vargjijo@in.ibm.com>
Signed-off-by: Nysal Jan K.A. <nysal@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240829022830.1164355-1-nysal@linux.ibm.com
Commit 6b0e82791bd0 ("powerpc/e500: switch to 64 bits PGD on 85xx
(32 bits)") switched PGD entries to 64 bits, but pgd_val() returns
an unsigned long which is 32 bits on PPC32. This is not a problem
for regular PMD entries because the upper part is always NULL, but
when PMD entries are leaf they contain 64 bits values, so pgd_val()
must return an unsigned long long instead of an unsigned long.
Also change the condition to CONFIG_PPC_85xx instead of CONFIG_PPC_E500
as the change was meant for 32 bits only. Allthough this should be
harmless on PPC64, it generates a warning with pgd_ERROR print.
Fixes: 6b0e82791bd0 ("powerpc/e500: switch to 64 bits PGD on 85xx (32 bits)")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/45f8fdf298ec3df7573b66d21b03a5cda92e2cb1.1724313510.git.christophe.leroy@csgroup.eu
After building the VDSO, there is a verification that it contains
no dynamic relocation, see commit aff69273af61 ("vdso: Improve
cmd_vdso_check to check all dynamic relocations").
This verification uses readelf -r and doesn't work if rela sections
are discarded.
Fixes: 8ad57add77d3 ("powerpc/build: vdso linker warning for orphan sections")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/45c3e6fc76cad05ad2cac0f5b5dfb4fae86dc9d6.1724153239.git.christophe.leroy@csgroup.eu
mmu_pte_psize is only used in the tlb_64e.c, define it static.
Fixes: 25d21ad6e799 ("powerpc: Add TLB management code for 64-bit Book3E")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202408011256.1O99IB0s-lkp@intel.com/
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/beb30d280eaa5d857c38a0834b147dffd6b28aa9.1724157750.git.christophe.leroy@csgroup.eu
topology_is_core_online() checks if the core a CPU belongs to
is online. The core is online if at least one of the sibling
CPUs is online. The first CPU of an online core is also online
in the common case, so this should be fairly quick.
Fixes: 73c58e7e1412 ("powerpc: Add HOTPLUG_SMT support")
Signed-off-by: Nysal Jan K.A <nysal@linux.ibm.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240731030126.956210-3-nysal@linux.ibm.com
Booting with CONFIG_DEBUG_VIRTUAL leads to following warning when
passing hugepage reservation on command line:
Kernel command line: hugepagesz=1g hugepages=1 hugepagesz=64m hugepages=1 hugepagesz=256m hugepages=1 noreboot
HugeTLB: allocating 1 of page size 1.00 GiB failed. Only allocated 0 hugepages.
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at arch/powerpc/include/asm/io.h:948 __alloc_bootmem_huge_page+0xd4/0x284
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 6.10.0-rc6-00396-g6b0e82791bd0-dirty #936
Hardware name: MPC8544DS e500v2 0x80210030 MPC8544 DS
NIP: c1020240 LR: c10201d0 CTR: 00000000
REGS: c13fdd30 TRAP: 0700 Not tainted (6.10.0-rc6-00396-g6b0e82791bd0-dirty)
MSR: 00021000 <CE,ME> CR: 44084288 XER: 20000000
GPR00: c10201d0 c13fde20 c130b560 e8000000 e8001000 00000000 00000000 c1420000
GPR08: 00000000 00028001 00000000 00000004 44084282 01066ac0 c0eb7c9c efffe149
GPR16: c0fc4228 0000005f ffffffff c0eb7d0c c0eb7cc0 c0eb7ce0 ffffffff 00000000
GPR24: c1441cec efffe153 e8001000 c14240c0 00000000 c1441d64 00000000 e8000000
NIP [c1020240] __alloc_bootmem_huge_page+0xd4/0x284
LR [c10201d0] __alloc_bootmem_huge_page+0x64/0x284
Call Trace:
[c13fde20] [c10201d0] __alloc_bootmem_huge_page+0x64/0x284 (unreliable)
[c13fde50] [c10207b8] hugetlb_hstate_alloc_pages+0x8c/0x3e8
[c13fdeb0] [c1021384] hugepages_setup+0x240/0x2cc
[c13fdef0] [c1000574] unknown_bootoption+0xfc/0x280
[c13fdf30] [c0078904] parse_args+0x200/0x4c4
[c13fdfa0] [c1000d9c] start_kernel+0x238/0x7d0
[c13fdff0] [c0000434] set_ivor+0x12c/0x168
Code: 554aa33e 7c042840 3ce0c142 80a7427c 5109a016 50caa016 7c9a2378 7fdcf378 4180000c 7c052040 41810160 7c095040 <0fe00000> 38c00000 40800108 3c60c0eb
---[ end trace 0000000000000000 ]---
This is due to virt_addr_valid() using high_memory before it is set.
high_memory is set in mem_init() using max_low_pfn, but max_low_pfn
is available long before, it is set in mem_topology_setup(). So just
like commit daa9ada2093e ("powerpc/mm: Fix boot crash with FLATMEM")
moved the setting of max_mapnr immediately after the call to
mem_topology_setup(), the same can be done for high_memory.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/62b69c4baad067093f39e7e60df0fe27a86b8d2a.1723100702.git.christophe.leroy@csgroup.eu
Commit 6b0e82791bd0 ("powerpc/e500: switch to 64 bits PGD on 85xx
(32 bits)") increased the size of PGD entries but failed to increase
the PGD directory.
Use the size of pgd_t instead of the size of pointers to calculate
the allocated size.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 6b0e82791bd0 ("powerpc/e500: switch to 64 bits PGD on 85xx (32 bits)")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/1cdaacb391cbd3e0240f0e0faf691202874e9422.1723109462.git.christophe.leroy@csgroup.eu
Pull more devicetree updates from Rob Herring:
"Most of this is a treewide change to of_property_for_each_u32() which
was small enough to do in one go before rc1 and avoids the need to
create of_property_for_each_u32_some_new_name().
- Treewide conversion of of_property_for_each_u32() to drop internal
arguments making struct property opaque
- Add binding for Amlogic A4 SoC watchdog
- Fix constraints for AD7192 'single-channel' property"
* tag 'devicetree-fixes-for-6.11-1' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux:
dt-bindings: iio: adc: ad7192: Fix 'single-channel' constraints
of: remove internal arguments from of_property_for_each_u32()
dt-bindings: watchdog: add support for Amlogic A4 SoCs
Pull struct file leak fixes from Al Viro: "a couple of leaks on failure exits missing fdput()" * tag 'pull-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: lirc: rc_dev_get_from_fd(): fix file leak powerpc: fix a file leak in kvm_vcpu_ioctl_enable_cap()
Pull driver core updates from Greg KH:
"Here is the big set of driver core changes for 6.11-rc1.
Lots of stuff in here, with not a huge diffstat, but apis are evolving
which required lots of files to be touched. Highlights of the changes
in here are:
- platform remove callback api final fixups (Uwe took many releases
to get here, finally!)
- Rust bindings for basic firmware apis and initial driver-core
interactions.
It's not all that useful for a "write a whole driver in rust" type
of thing, but the firmware bindings do help out the phy rust
drivers, and the driver core bindings give a solid base on which
others can start their work.
There is still a long way to go here before we have a multitude of
rust drivers being added, but it's a great first step.
- driver core const api changes.
This reached across all bus types, and there are some fix-ups for
some not-common bus types that linux-next and 0-day testing shook
out.
This work is being done to help make the rust bindings more safe,
as well as the C code, moving toward the end-goal of allowing us to
put driver structures into read-only memory. We aren't there yet,
but are getting closer.
- minor devres cleanups and fixes found by code inspection
- arch_topology minor changes
- other minor driver core cleanups
All of these have been in linux-next for a very long time with no
reported problems"
* tag 'driver-core-6.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (55 commits)
ARM: sa1100: make match function take a const pointer
sysfs/cpu: Make crash_hotplug attribute world-readable
dio: Have dio_bus_match() callback take a const *
zorro: make match function take a const pointer
driver core: module: make module_[add|remove]_driver take a const *
driver core: make driver_find_device() take a const *
driver core: make driver_[create|remove]_file take a const *
firmware_loader: fix soundness issue in `request_internal`
firmware_loader: annotate doctests as `no_run`
devres: Correct code style for functions that return a pointer type
devres: Initialize an uninitialized struct member
devres: Fix memory leakage caused by driver API devm_free_percpu()
devres: Fix devm_krealloc() wasting memory
driver core: platform: Switch to use kmemdup_array()
driver core: have match() callback in struct bus_type take a const *
MAINTAINERS: add Rust device abstractions to DRIVER CORE
device: rust: improve safety comments
MAINTAINERS: add Danilo as FIRMWARE LOADER maintainer
MAINTAINERS: add Rust FW abstractions to FIRMWARE LOADER
firmware: rust: improve safety comments
...