The patch titled x86/uv: make kdump avoid stack dumps has been added to the -mm tree. Its filename is x86-uv-make-kdump-avoid-stack-dumps.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: x86/uv: make kdump avoid stack dumps From: Cliff Wickman <cpw@xxxxxxx> UV NMI callback's should not write stack dumps when a kdump is to be written. When invoking the crash kernel to write a dump, kdump_nmi_shootdown_cpus() uses NMI's to get all the cpu's to save their register context and halt. But the NMI interrupt handler runs a callback list. This patch sets a flag to prevent any of those callbacks from interfering with the halt of the cpu. For UV, which currently has the only callback to which this is relevant, the uv_handle_nmi() callback should not do dumping of stacks. The 'in_crash_kexec' flag is defined as an extern in kdebug.h firstly because x2apic_uv_x.c includes it. Secondly because some future callback might need the flag to know that it should not enter the debugger. (Such a scenario was in fact present in the 2.6.32 kernel, SuSE distribution, where a call to kdb needed to be avoided.) Signed-off-by: Cliff Wickman <cpw@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/x86/include/asm/kdebug.h | 6 ++++++ arch/x86/kernel/apic/x2apic_uv_x.c | 4 ++++ arch/x86/kernel/crash.c | 3 +++ 3 files changed, 13 insertions(+) diff -puN arch/x86/include/asm/kdebug.h~x86-uv-make-kdump-avoid-stack-dumps arch/x86/include/asm/kdebug.h --- a/arch/x86/include/asm/kdebug.h~x86-uv-make-kdump-avoid-stack-dumps +++ a/arch/x86/include/asm/kdebug.h @@ -33,5 +33,11 @@ extern void __show_regs(struct pt_regs * extern void show_regs(struct pt_regs *regs); extern unsigned long oops_begin(void); extern void oops_end(unsigned long, struct pt_regs *, int signr); +#ifdef CONFIG_KEXEC +extern int in_crash_kexec; +#else +/* no crash dump is ever in progress if no crash kernel can be kexec'd */ +#define in_crash_kexec 0 +#endif #endif /* _ASM_X86_KDEBUG_H */ diff -puN arch/x86/kernel/apic/x2apic_uv_x.c~x86-uv-make-kdump-avoid-stack-dumps arch/x86/kernel/apic/x2apic_uv_x.c --- a/arch/x86/kernel/apic/x2apic_uv_x.c~x86-uv-make-kdump-avoid-stack-dumps +++ a/arch/x86/kernel/apic/x2apic_uv_x.c @@ -604,6 +604,10 @@ int uv_handle_nmi(struct notifier_block { if (reason != DIE_NMI_IPI) return NOTIFY_OK; + + if (in_crash_kexec) + /* do nothing if entering the crash kernel */ + return NOTIFY_OK; /* * Use a lock so only one cpu prints at a time * to prevent intermixed output. diff -puN arch/x86/kernel/crash.c~x86-uv-make-kdump-avoid-stack-dumps arch/x86/kernel/crash.c --- a/arch/x86/kernel/crash.c~x86-uv-make-kdump-avoid-stack-dumps +++ a/arch/x86/kernel/crash.c @@ -28,6 +28,8 @@ #include <asm/reboot.h> #include <asm/virtext.h> +int in_crash_kexec; + #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) static void kdump_nmi_callback(int cpu, struct die_args *args) @@ -61,6 +63,7 @@ static void kdump_nmi_callback(int cpu, static void kdump_nmi_shootdown_cpus(void) { + in_crash_kexec = 1; nmi_shootdown_cpus(kdump_nmi_callback); disable_local_APIC(); _ Patches currently in -mm which might be from cpw@xxxxxxx are linux-next.patch x86-uv-make-kdump-avoid-stack-dumps.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html