Hi Lianbo, Tao When CPUs are in an offline state, it can lead to mapping errors.

We need to map them to the correct positions one by one.

Before:

n_namesz: 5 ("CPU2") n_descsz: 392 n_type: 1 (NT_PRSTATUS) si.signo: 0 si.code: 0 si.errno: 0 cursig: 0 sigpend: 0 sighold: 0 pid: 3 ppid: 0 pgrp: 0 sid:0 utime: 0.000000 stime: 0.000000 cutime: 0.000000 cstime: 0.000000

X0: ffffffc000fc8818 X1: 0000000000000000 X2: ffffffc000fc84c8 X3: 0000000000000000 X4: ffffffc0405e37bf X5: ffffffc00a07372f X6: 322e34323320205b X7: 545b5d3539383334 X8: ffffffc000fc2f0c X9: 89fece0a9ef8cb00 X10: c0000001001f75f4 X11: 00000001001f75f4 X12: 0000000000000003 X13: 00000000000005f4 X14: ffffffc009eb1210 X15: 0000000000000004 X16: 000000002a4cec24 X17: 000000002a4cec24 X18: ffffffc009e7d140 X19: ffffffc00a04c670 X20: 0000000000000000 X21: 0000000000000000 X22: ffffff8027f22280 X23: 0000000000000009 X24: 0000000000000007 X25: ffffffc009f839c0 X26: ffffffc0090f87f8 X27: 0000000000000000 X28: ffffff80454f3840 X29: ffffffc0405e3b60 LR: ffffffc0080e57fc SP: ffffffc0405e3b60 PC: ffffffc000fc2f84

CPU 0: [OFFLINE] CPU 1: [OFFLINE] CPU 2: X0: 0000000000000000 X1: 0000000000000000 X2: 0000000000000000 X3: 000000000003fcbc X4: 0000000000000001 X5: 0000000000000000 X6: 0000000000000000 X7: 0000000000000000 X8: 00000000ffffffff X9: ffffffc009e6ae48 X10: ffffffc009e6ae20 X11: 0000000000000000 X12: 0000000000000002 X13: 0000000000000004 X14: 0000000000000000 X15: 0000000000004000 X16: 00000000f90f05f6 X17: 00000000f90f05f6 X18: 0000000000000000 X19: 0000000000000002 X20: ffffffc009e3b008 X21: ffffffc00a01d020 X22: ffffffc009f798f0 X23: 0000000060001000 X24: 0000000000000000 X25: 0000000000000000 X26: 0000000000000000 X27: 0000000000000000 X28: ffffff8111eecb00 X29: ffffffc008003f50 LR: ffffffc00802df88 SP: ffffffc008003f40 PC: ffffffc00802df94 PSTATE: 024003c5 FPVALID: 00000000 After: CPU 2: X0: ffffffc000fc8818 X1: 0000000000000000 X2: ffffffc000fc84c8 X3: 0000000000000000 X4: ffffffc0405e37bf X5: ffffffc00a07372f X6: 322e34323320205b X7: 545b5d3539383334 X8: ffffffc000fc2f0c X9: 89fece0a9ef8cb00 X10: c0000001001f75f4 X11: 00000001001f75f4 X12: 0000000000000003 X13: 00000000000005f4 X14: ffffffc009eb1210 X15: 0000000000000004 X16: 000000002a4cec24 X17: 000000002a4cec24 X18: ffffffc009e7d140 X19: ffffffc00a04c670 X20: 0000000000000000 X21: 0000000000000000 X22: ffffff8027f22280 X23: 0000000000000009 X24: 0000000000000007 X25: ffffffc009f839c0 X26: ffffffc0090f87f8 X27: 0000000000000000 X28: ffffff80454f3840 X29: ffffffc0405e3b60

LR: ffffffc0080e57fc SP: ffffffc0405e3b60 PC: ffffffc000fc2f84 PSTATE: 600000c5 FPVALID: 00000000 crash> bt PID: 15959 TASK: ffffff80454f3840 CPU: 2 COMMAND: "AnrConsumer" [ffffffc0405e3b60] ipanic at ffffffc000fc2f80 [mrdump] [ffffffc0405e3b70] atomic_notifier_call_chain at ffffffc0080e57f8 [ffffffc0405e3c30] panic at ffffffc008f734d0 [ffffffc0405e3c80] sysrq_handle_crash at ffffffc0087f3c18 [ffffffc0405e3c90] __handle_sysrq at ffffffc0087f3798 [ffffffc0405e3ce0] write_sysrq_trigger at ffffffc0087f49c0 [ffffffc0405e3d00] proc_reg_write at ffffffc00842e4b8 [ffffffc0405e3d80] vfs_write at ffffffc008381eb4 [ffffffc0405e3dd0] ksys_write at ffffffc008382200 [ffffffc0405e3e10] __arm64_sys_write at ffffffc00838228c [ffffffc0405e3e20] invoke_syscall at ffffffc00802efe0 [ffffffc0405e3e40] el0_svc_common at ffffffc00802eef4 [ffffffc0405e3e70] do_el0_svc at ffffffc00802ede8 [ffffffc0405e3e80] el0_svc at ffffffc008f7a7d0 [ffffffc0405e3ea0] el0t_64_sync_handler at ffffffc008f7a758 [ffffffc0405e3fe0] el0t_64_sync at ffffffc00801157c

PC: 00000077c798ca28 LR: 00000077a82e19f4 SP: 000000761c517af0 X29: 000000761c517b00 X28: 000000761c517db8 X27: 000000761c517c90 X26: 000000761c517c98 X25: 000000761c517bf9 X24: 000000761c519000 X23: 000000761c517be1 X22: 0000000000000001 X21: 00000000000003e3 X20: 000000761c517c11 X19: 000000761c517bf8 X18: 0000007568224000 X17: 00000077c798ca20 X16: 00000077c79b2ae0 X15: b4000077202cc480 X14: 0000000000000000 X13: 000000761c517a70 X12: ffffff80ffffffd0 X11: 000000761c517a40 X10: 0000000000000001 X9: 0000000000000000 X8: 0000000000000040 X7: 7f7f7f7f7f7f7f7f X6: 0000000000000010 X5: 000000761c517c0c X4: ffffffffffffffff X3: ffffffffffffffff X2: 0000000000000001 X1: 000000761c517c11 X0: 00000000000003e3 ORIG_X0: 00000000000003e3 SYSCALLNO: 40 PSTATE: 00001000

Signed-off-by: Guanyou.Chen <chenguanyou(a)xiaomi.com&gt; --- netdump.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/netdump.c b/netdump.c index b4e2a5c..8ea5159 100644 --- a/netdump.c +++ b/netdump.c @@ -75,7 +75,7 @@ void map_cpus_to_prstatus(void) { void **nt_ptr; - int online, i, j, nrcpus; + int online, i, nrcpus; size_t size; if (pc->flags2 & QEMU_MEM_DUMP_ELF) /* notes exist for all cpus */ @@ -100,9 +100,9 @@ map_cpus_to_prstatus(void) */ nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS); - for (i = 0, j = 0; i < nrcpus; i++) { + for (i = 0; i < nrcpus; i++) { if (in_cpu_map(ONLINE_MAP, i) && machdep->is_cpu_prstatus_valid(i)) { - nd->nt_prstatus_percpu[i] = nt_ptr[j++]; + nd->nt_prstatus_percpu[i] = nt_ptr[i]; nd->num_prstatus_notes = MAX(nd->num_prstatus_notes, i+1); } -- 2.34.1 Guanyou. Thanks.

Hi Tao > 1. What is the root cause, why cpu offline state will lead to mapping > errors? You didn't make this clear in your commit message. The back CPU context wrong order When the front CPU is offline. exp: CPU0, CPU1 is offline, CPU2 is online, CPU2's nt_prstatus_percpu from corefile note prstatus[0], because i, j not equal. > 2. Is this issue cpu arch specific? Since the example you gave is only > arm64 specific, however the code change is generic for all archs. So > I'm a bit worried about whether it will make the result incorrect for > other archs. In addition, I didn't reproduce the mapping error issue > on my x86_64 machine, so I cannot verify the patch locally. N/A > What command line you trigger will get the following outputs? $ crash vmlinux vmcore -d 1 crash> help -r Thanks, Guanyou Tao Liu <ltao(a)redhat.com&gt; 于2024年11月21日周四 13:42写道： > > Hi Guanyou, > > Thanks for the fix. However I have a few questions for this patch: > > On Fri, Nov 1, 2024 at 10:16 PM Guanyou Chen <chenguanyou9338(a)gmail.com&gt; wrote: > > > > Hi Lianbo, Tao > > > > When CPUs are in an offline state, it can lead to mapping errors. > > 1. What is the root cause, why cpu offline state will lead to mapping > errors? You didn't make this clear in your commit message. > 2. Is this issue cpu arch specific? Since the example you gave is only > arm64 specific, however the code change is generic for all archs. So > I'm a bit worried about whether it will make the result incorrect for > other archs. In addition, I didn't reproduce the mapping error issue > on my x86_64 machine, so I cannot verify the patch locally. > > > We need to map them to the correct positions one by one. > > > > 3. Please make the commit log tidy. I know you want to diff the > outputs of "before" and "after", but we only need the info which are > highly related to this issue. e.g: > > > Before: > > What command line you trigger will get the following outputs? > > > n_namesz: 5 ("CPU2") > > n_descsz: 392 > > n_type: 1 (NT_PRSTATUS) > > si.signo: 0 si.code: 0 si.errno: 0 > > cursig: 0 sigpend: 0 sighold: 0 > > pid: 3 ppid: 0 pgrp: 0 sid:0 > > utime: 0.000000 stime: 0.000000 > > cutime: 0.000000 cstime: 0.000000 > > I'm not sure if the above info is related to this issue? > > > X0: ffffffc000fc8818 X1: 0000000000000000 X2: ffffffc000fc84c8 > > X3: 0000000000000000 X4: ffffffc0405e37bf X5: ffffffc00a07372f > > X6: 322e34323320205b X7: 545b5d3539383334 X8: ffffffc000fc2f0c > > X9: 89fece0a9ef8cb00 X10: c0000001001f75f4 X11: 00000001001f75f4 > > X12: 0000000000000003 X13: 00000000000005f4 X14: ffffffc009eb1210 > > X15: 0000000000000004 X16: 000000002a4cec24 X17: 000000002a4cec24 > > X18: ffffffc009e7d140 X19: ffffffc00a04c670 X20: 0000000000000000 > > X21: 0000000000000000 X22: ffffff8027f22280 X23: 0000000000000009 > > X24: 0000000000000007 X25: ffffffc009f839c0 X26: ffffffc0090f87f8 > > X27: 0000000000000000 X28: ffffff80454f3840 X29: ffffffc0405e3b60 > > LR: ffffffc0080e57fc SP: ffffffc0405e3b60 PC: ffffffc000fc2f84 > > We don't need a list of all regs, a few lines of which can indicate > the output mismatch for "Before" and "After" is enough. > > > > > CPU 0: [OFFLINE] > > CPU 1: [OFFLINE] > > CPU 2: > > X0: 0000000000000000 X1: 0000000000000000 X2: 0000000000000000 > > X3: 000000000003fcbc X4: 0000000000000001 X5: 0000000000000000 > > X6: 0000000000000000 X7: 0000000000000000 X8: 00000000ffffffff > > X9: ffffffc009e6ae48 X10: ffffffc009e6ae20 X11: 0000000000000000 > > X12: 0000000000000002 X13: 0000000000000004 X14: 0000000000000000 > > X15: 0000000000004000 X16: 00000000f90f05f6 X17: 00000000f90f05f6 > > X18: 0000000000000000 X19: 0000000000000002 X20: ffffffc009e3b008 > > X21: ffffffc00a01d020 X22: ffffffc009f798f0 X23: 0000000060001000 > > X24: 0000000000000000 X25: 0000000000000000 X26: 0000000000000000 > > X27: 0000000000000000 X28: ffffff8111eecb00 X29: ffffffc008003f50 > > LR: ffffffc00802df88 SP: ffffffc008003f40 PC: ffffffc00802df94 > > PSTATE: 024003c5 FPVALID: 00000000 > > > > After: > > CPU 2: > > X0: ffffffc000fc8818 X1: 0000000000000000 X2: ffffffc000fc84c8 > > X3: 0000000000000000 X4: ffffffc0405e37bf X5: ffffffc00a07372f > > X6: 322e34323320205b X7: 545b5d3539383334 X8: ffffffc000fc2f0c > > X9: 89fece0a9ef8cb00 X10: c0000001001f75f4 X11: 00000001001f75f4 > > X12: 0000000000000003 X13: 00000000000005f4 X14: ffffffc009eb1210 > > X15: 0000000000000004 X16: 000000002a4cec24 X17: 000000002a4cec24 > > X18: ffffffc009e7d140 X19: ffffffc00a04c670 X20: 0000000000000000 > > X21: 0000000000000000 X22: ffffff8027f22280 X23: 0000000000000009 > > X24: 0000000000000007 X25: ffffffc009f839c0 X26: ffffffc0090f87f8 > > X27: 0000000000000000 X28: ffffff80454f3840 X29: ffffffc0405e3b60 > > > LR: ffffffc0080e57fc SP: ffffffc0405e3b60 PC: ffffffc000fc2f84 > > PSTATE: 600000c5 FPVALID: 00000000 > > > > crash> bt > > PID: 15959 TASK: ffffff80454f3840 CPU: 2 COMMAND: "AnrConsumer" > > [ffffffc0405e3b60] ipanic at ffffffc000fc2f80 [mrdump] > > [ffffffc0405e3b70] atomic_notifier_call_chain at ffffffc0080e57f8 > > [ffffffc0405e3c30] panic at ffffffc008f734d0 > > [ffffffc0405e3c80] sysrq_handle_crash at ffffffc0087f3c18 > > [ffffffc0405e3c90] __handle_sysrq at ffffffc0087f3798 > > [ffffffc0405e3ce0] write_sysrq_trigger at ffffffc0087f49c0 > > [ffffffc0405e3d00] proc_reg_write at ffffffc00842e4b8 > > [ffffffc0405e3d80] vfs_write at ffffffc008381eb4 > > [ffffffc0405e3dd0] ksys_write at ffffffc008382200 > > [ffffffc0405e3e10] __arm64_sys_write at ffffffc00838228c > > [ffffffc0405e3e20] invoke_syscall at ffffffc00802efe0 > > [ffffffc0405e3e40] el0_svc_common at ffffffc00802eef4 > > [ffffffc0405e3e70] do_el0_svc at ffffffc00802ede8 > > [ffffffc0405e3e80] el0_svc at ffffffc008f7a7d0 > > [ffffffc0405e3ea0] el0t_64_sync_handler at ffffffc008f7a758 > > [ffffffc0405e3fe0] el0t_64_sync at ffffffc00801157c > > The stacktrace is meaningless for this patch, we can cut this off. > > > PC: 00000077c798ca28 LR: 00000077a82e19f4 SP: 000000761c517af0 > > X29: 000000761c517b00 X28: 000000761c517db8 X27: 000000761c517c90 > > X26: 000000761c517c98 X25: 000000761c517bf9 X24: 000000761c519000 > > X23: 000000761c517be1 X22: 0000000000000001 X21: 00000000000003e3 > > X20: 000000761c517c11 X19: 000000761c517bf8 X18: 0000007568224000 > > X17: 00000077c798ca20 X16: 00000077c79b2ae0 X15: b4000077202cc480 > > X14: 0000000000000000 X13: 000000761c517a70 X12: ffffff80ffffffd0 > > X11: 000000761c517a40 X10: 0000000000000001 X9: 0000000000000000 > > X8: 0000000000000040 X7: 7f7f7f7f7f7f7f7f X6: 0000000000000010 > > X5: 000000761c517c0c X4: ffffffffffffffff X3: ffffffffffffffff > > X2: 0000000000000001 X1: 000000761c517c11 X0: 00000000000003e3 > > ORIG_X0: 00000000000003e3 SYSCALLNO: 40 PSTATE: 00001000 > > > ditto. > > Maybe a short summary after the output paste, telling us which info > should reviewers pay attention to. > > Thanks, > Tao Liu > > > Signed-off-by: Guanyou.Chen <chenguanyou(a)xiaomi.com&gt; > > --- > > netdump.c | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/netdump.c b/netdump.c > > index b4e2a5c..8ea5159 100644 > > --- a/netdump.c > > +++ b/netdump.c > > @@ -75,7 +75,7 @@ void > > map_cpus_to_prstatus(void) > > { > > void **nt_ptr; > > - int online, i, j, nrcpus; > > + int online, i, nrcpus; > > size_t size; > > > > if (pc->flags2 & QEMU_MEM_DUMP_ELF) /* notes exist for all cpus */ > > @@ -100,9 +100,9 @@ map_cpus_to_prstatus(void) > > */ > > nrcpus = (kt->kernel_NR_CPUS ? kt->kernel_NR_CPUS : NR_CPUS); > > > > - for (i = 0, j = 0; i < nrcpus; i++) { > > + for (i = 0; i < nrcpus; i++) { > > if (in_cpu_map(ONLINE_MAP, i) && machdep->is_cpu_prstatus_valid(i)) { > > - nd->nt_prstatus_percpu[i] = nt_ptr[j++]; > > + nd->nt_prstatus_percpu[i] = nt_ptr[i];

> > nd->num_prstatus_notes = > > MAX(nd->num_prstatus_notes, i+1); > > } > > -- > > 2.34.1 > > > > Guanyou. > > Thanks. >