| Message ID | 147733331174.26684.12646675491489853468.stgit@jupiter.in.ibm.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Mon, 2016-10-24 at 18:21:51 UTC, Mahesh Salgaonkar wrote: > From: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> > > There are chances that multiple CPUs can call crash_fadump() simultaneously > and would start duplicating same info to vmcoreinfo ELF note section. This > causes makedumpfile to fail during kdump capture. One example is, > triggering dumprestart from HMC which sends system reset to all the CPUs at > once. > > makedumpfile --dump-dmesg /proc/vmcore > read_vmcoreinfo_basic_info: Invalid data in /tmp/vmcoreinfoyjgxlL: CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971 > makedumpfile Failed. > Running makedumpfile --dump-dmesg /proc/vmcore failed (1). > > makedumpfile -d 31 -l /proc/vmcore > read_vmcoreinfo_basic_info: Invalid data in /tmp/vmcoreinfo1mmVdO: CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971CRASHTIME=1475605971 > makedumpfile Failed. > Running makedumpfile -d 31 -l /proc/vmcore failed (1). > > Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/f2a5e8f0023eba847ad2adb145b2f6 cheers
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index b3a6633..a795956 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -401,12 +401,35 @@ static void register_fw_dump(struct fadump_mem_struct *fdm) void crash_fadump(struct pt_regs *regs, const char *str) { struct fadump_crash_info_header *fdh = NULL; + int old_cpu, this_cpu; if (!fw_dump.dump_registered || !fw_dump.fadumphdr_addr) return; + /* + * old_cpu == -1 means this is the first CPU which has come here, + * go ahead and trigger fadump. + * + * old_cpu != -1 means some other CPU has already on it's way + * to trigger fadump, just keep looping here. + */ + this_cpu = smp_processor_id(); + old_cpu = cmpxchg(&crashing_cpu, -1, this_cpu); + + if (old_cpu != -1) { + /* + * We can't loop here indefinitely. Wait as long as fadump + * is in force. If we race with fadump un-registration this + * loop will break and then we go down to normal panic path + * and reboot. If fadump is in force the first crashing + * cpu will definitely trigger fadump. + */ + while (fw_dump.dump_registered) + cpu_relax(); + return; + } + fdh = __va(fw_dump.fadumphdr_addr); - crashing_cpu = smp_processor_id(); fdh->crashing_cpu = crashing_cpu; crash_save_vmcoreinfo();