diff options
| author |   Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> | 2015-12-14 11:19:11 +0100 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2015-12-19 11:07:01 +0100 |
| commit | 7bbee5ca3896f69f09c68be549cb8997abe6bca6 (patch) | |
| tree | aa2ffe78b5f70617f6fec0da5d3075962bf392d2 /include/linux/kexec.h | |
| parent | panic, x86: Allow CPUs to save registers even if looping in NMI context (diff) | |
| download | linux-dev-7bbee5ca3896f69f09c68be549cb8997abe6bca6.tar.xz linux-dev-7bbee5ca3896f69f09c68be549cb8997abe6bca6.zip | |
kexec: Fix race between panic() and crash_kexec()
Currently, panic() and crash_kexec() can be called at the same time.
For example (x86 case):
CPU 0:
oops_end()
crash_kexec()
mutex_trylock() // acquired
nmi_shootdown_cpus() // stop other CPUs
CPU 1:
panic()
crash_kexec()
mutex_trylock() // failed to acquire
smp_send_stop() // stop other CPUs
infinite loop
If CPU 1 calls smp_send_stop() before nmi_shootdown_cpus(), kdump
fails.
In another case:
CPU 0:
oops_end()
crash_kexec()
mutex_trylock() // acquired
<NMI>
io_check_error()
panic()
crash_kexec()
mutex_trylock() // failed to acquire
infinite loop
Clearly, this is an undesirable result.
To fix this problem, this patch changes crash_kexec() to exclude others
by using the panic_cpu atomic.
Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: kexec@lists.infradead.org
Cc: linux-doc@vger.kernel.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Minfei Huang <mnfhuang@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/20151210014630.25437.94161.stgit@softrs
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/linux/kexec.h')
| -rw-r--r-- | include/linux/kexec.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/kexec.h b/include/linux/kexec.h index d140b1e9faa7..7b68d2788a56 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -237,6 +237,7 @@ extern int kexec_purgatory_get_set_symbol(struct kimage *image, unsigned int size, bool get_value); extern void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name); +extern void __crash_kexec(struct pt_regs *); extern void crash_kexec(struct pt_regs *); int kexec_should_crash(struct task_struct *); void crash_save_cpu(struct pt_regs *regs, int cpu); @@ -332,6 +333,7 @@ int __weak arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, #else /* !CONFIG_KEXEC_CORE */ struct pt_regs; struct task_struct; +static inline void __crash_kexec(struct pt_regs *regs) { } static inline void crash_kexec(struct pt_regs *regs) { } static inline int kexec_should_crash(struct task_struct *p) { return 0; } #define kexec_in_progress false |