Hi Lucas, Thanks for the fix. On Fri, Apr 24, 2026 at 9:17 AM Lucas Oakley <soakley(a)redhat.com&gt; wrote: > > In RHEL 9.4 ppc64le, the stack size was adjusted from 16k to > 32k. As a result, ppc64_back_trace() can bail prematurely when > checking if the stack pointer exists in the range of the > range of the irq stacks, since SIZE(irq_ctx), used in > ppc64_in_irqstack(), is set to 16k. This patch ensures that > irq_ctx is updated to 32k if a 32k stack size is used. > > Tested against: > el6 x86_64 > el7 ppc64le s390x x86_64 > el8 aarch64 ppc64le s390x x86_64 > el9 aarch64 ppc64le s390x x86_64 > el10 aarch64 ppc64le s390x x86_64 > > Without the commit: > > crash> bt -c 3 > PID: 17524 TASK: c0000000b2c0e400 CPU: 3 COMMAND: "xyz" > cannot find the stack info. > > With the commit: > > crash> bt -c 3 > PID: 17524 TASK: c0000000b2c0e400 CPU: 3 COMMAND: "xyz" > #0 [c000001dff7d7c10] smp_call_function_single_async at c00000000028dd38 > #1 [c000001dff7d7d30] _raw_spin_lock_irqsave at c000000001023f1c > #2 [c000001dff7d7d60] ibmvscsi_handle_crq at c0080000044635ec [ibmvscsi] > #3 [c000001dff7d7de0] ibmvscsi_task at c008000004463804 [ibmvscsi] > #4 [c000001dff7d7e30] tasklet_action_common.constprop.0 at c0000000001624cc > #5 [c000001dff7d7e90] __do_softirq at c0000000010244cc > #6 [c000001dff7d7f90] do_softirq_own_stack at c000000000016480 > #7 [c000000140d67700] __irq_exit_rcu at c0000000001613b8 > #8 [c000000140d67730] irq_exit at c000000000162170 > #9 [c000000140d67750] do_IRQ at c000000000015fa4 > #10 [c000000140d67780] hardware_interrupt_common_virt at c000000000009080 > Hardware Interrupt [500] exception frame: > R0: c000000001023de0 R1: c000000140d67a90 R2: c000000002c02500 > R3: c00800000b30269c R4: 0000000000000001 R5: 0000000000000001 > R6: ffffffffffffffff R7: 0000000000000000 R8: 0000000000000000 > R9: fffffffffffe0000 R10: 0000000000000002 R11: 0000000048422824 > R12: c000000001023d70 R13: c000001dffffd480 R14: 00007ffd6ef6d238 > R15: 0000000000000028 R16: c000001dfc1e2280 R17: c000001dfc1e2280 > R18: 00000000ab97fa48 R19: 0000000000000000 R20: 0000000000000001 > R21: 0000001df9ff0000 R22: 0000000000000028 R23: c0000000021f2280 > R24: 0000000000000000 R25: c0000000021f2280 R26: c0000000021f2380 > R27: 0000000000000000 R28: c00800000b30269c R29: 0000000000000000 > R30: c000000002c47190 R31: 000000000020000b > NIP: c0000000000aea14 MSR: 800000000280b033 OR3: c0000000000ae944 > CTR: c000000001023d70 LR: c000000001023de0 XER: 0000000020040001 > CCR: 0000000088422824 MQ: 0000000000000000 DAR: 0000000000000001 > DSISR: c0080000073b1e94 Syscall Result: 0000000000000000 > [NIP : queued_spin_lock_slowpath+1204] > [LR : _raw_spin_lock+112] > #11 [c000000140d67a90] queued_spin_lock_slowpath at c0000000000aea14 > #12 [c000000140d67bb0] _raw_spin_lock at c000000001023de0 (unreliable) > #13 [c000000140d67bd0] dm_blk_close at c00800000b2c6850 [dm_mod] > #14 [c000000140d67c00] blkdev_put_whole at c0000000007d2738 > #15 [c000000140d67c30] bdev_release at c0000000007d3a38 > #16 [c000000140d67c90] blkdev_release at c0000000007d4224 > #17 [c000000140d67cb0] __fput at c0000000005d2e98 > #18 [c000000140d67d00] task_work_run at c00000000018fb14 > #19 [c000000140d67d50] do_notify_resume at c000000000020bd4 > #20 [c000000140d67d80] interrupt_exit_user_prepare_main at c00000000002ed98 > #21 [c000000140d67de0] syscall_exit_prepare at c00000000002f240 > #22 [c000000140d67e10] system_call_vectored_common at c00000000000bff4 > > Signed-off-by: Lucas Oakley <soakley(a)redhat.com&gt; > --- > task.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/task.c b/task.c > index ec04b55..a398a8d 100644 > --- a/task.c > +++ b/task.c > @@ -739,6 +739,18 @@ irqstacks_init(void) > if (!(tt->softirq_tasks = (ulong *)calloc(NR_CPUS, sizeof(ulong)))) > error(FATAL, "cannot malloc softirq_tasks space."); > > + /* > + * RHEL 9.4.z adjusted the stack size from 16k to 32k for > + * ppc64le only. We need to ensure that SIZE(irq_ctx) is > + * correctly set so the unwinder doesn't prematurely bail > + * when switching between the kernel stack and irq stacks. > + * The stack size is updated in task_init(), which calls > + * this routine, irqstacks_init() after checking for the > + * existence of irq_ctx. > + */ > + if ((SIZE(irq_ctx) != -1) && (STACKSIZE() > SIZE(irq_ctx))) > + ASSIGN_SIZE(irq_ctx) = STACKSIZE(); > + I think the (SIZE(irq_ctx) != -1) check is not needed. Because when entering the function, VALID_STRUCT(irq_ctx) already ensure size_table.irq_ctx >= 0, so (SIZE(irq_ctx) != -1) is always true. I have no other concerns for the patch. Thanks, Tao Liu > thread_info_buf = GETBUF(SIZE(irq_ctx)); > > if ((hard_sp = per_cpu_symbol_search("per_cpu__hardirq_ctx")) || > -- > 2.52.0 > -- > Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io > To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io > https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ > Contribution Guidelines: https://github.com/crash-utility/crash/wiki >