Re: [RFC PATCH 00/17][request for stable 3.10 inclusion] x86/nmi: Print all cpu stacks from NMI safely
On 2015/5/14 21:55, Steven Rostedt wrote: > On Thu, 14 May 2015 11:34:47 + > Wang Long wrote: > >> The patch 1-13 backport the "seq_buf" infrastructures. in detail, patch 1, 2 >> and 6 only backport "seq_buf" related code. >> > > Ah, so basically you just backported the seq_buf.c code without > modifying the trace_seq code. That's a good approach. I don't have much > time to look at these but I'll try to skim them to see if I find > anything broken. > > I may pull all of them into a test branch and run my tests to make sure > they don't break anything else. > > -- Steve > Hi Steve, Thank you for your review and test. Does your testcases run OK with this series patches? Best Regards Wang Long > >> arch/x86/kernel/apic/hw_nmi.c | 86 +- >> include/linux/percpu.h| 4 + >> include/linux/printk.h| 2 + >> include/linux/seq_buf.h | 136 >> kernel/printk.c | 41 +++-- >> lib/Makefile | 2 +- >> lib/seq_buf.c | 359 >> ++ >> 7 files changed, 617 insertions(+), 13 deletions(-) >> create mode 100644 include/linux/seq_buf.h >> create mode 100644 lib/seq_buf.c >> > > > . > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [RFC PATCH 00/17][request for stable 3.10 inclusion] x86/nmi: Print all cpu stacks from NMI safely
On Thu, 14 May 2015 11:34:47 + Wang Long wrote: > The patch 1-13 backport the "seq_buf" infrastructures. in detail, patch 1, 2 > and 6 only backport "seq_buf" related code. > Ah, so basically you just backported the seq_buf.c code without modifying the trace_seq code. That's a good approach. I don't have much time to look at these but I'll try to skim them to see if I find anything broken. I may pull all of them into a test branch and run my tests to make sure they don't break anything else. -- Steve > arch/x86/kernel/apic/hw_nmi.c | 86 +- > include/linux/percpu.h| 4 + > include/linux/printk.h| 2 + > include/linux/seq_buf.h | 136 > kernel/printk.c | 41 +++-- > lib/Makefile | 2 +- > lib/seq_buf.c | 359 > ++ > 7 files changed, 617 insertions(+), 13 deletions(-) > create mode 100644 include/linux/seq_buf.h > create mode 100644 lib/seq_buf.c > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[RFC PATCH 00/17][request for stable 3.10 inclusion] x86/nmi: Print all cpu stacks from NMI safely
This is my backport patch series to Fix the problem(backport to 3.10): " When trigger_all_cpu_backtrace() is called on x86, it will trigger an NMI on each CPU and call show_regs(). But this can lead to a hard lock up if the NMI comes in on another printk(). " The solution is described in commit "a9edc88093287183ac934be44f295f183b2c62dd": when the NMI triggers, it switches the printk routine for that CPU to call a NMI safe printk function that records the printk in a per_cpu seq_buf descriptor. After all NMIs have finished recording its data, the trace_ seqs are printed in a safe context. The solution use "switch printk routine" and "seq_buf" infrastructures, but the 3.10 stable have no both of them. The patch 1-13 backport the "seq_buf" infrastructures. in detail, patch 1, 2 and 6 only backport "seq_buf" related code. The patch 14-15 backport the "switch printk routine". The patch 16-17 is the patch to print all cpu stacks from NMI safely as discussed in https://lkml.org/lkml/2015/5/13/497, in 3.10 stable, this is the only way to solve the problem and the backport code is a bit more. Any thoughts? Sasha Levin (1): x86/nmi: Fix use of unallocated cpumask_var_t Steven Rostedt (Red Hat) (16): tracing: Create seq_buf layer in trace_seq tracing: Convert seq_buf_path() to be like seq_path() tracing: Convert seq_buf fields to be like seq_file fields tracing: Add a seq_buf_clear() helper and clear len and readpos in init seq_buf: Create seq_buf_used() to find out how much was written tracing: Use trace_seq_used() and seq_buf_used() instead of len seq_buf: Add seq_buf_can_fit() helper function tracing: Have seq_buf use full buffer tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF seq_buf: Move the seq_buf code to lib/ seq_buf: Fix seq_buf_vprintf() truncation seq_buf: Fix seq_buf_bprintf() truncation printk: Add per_cpu printk func to allow printk to be diverted printk/percpu: Define printk_func when printk is not defined x86/nmi: Perform a safe NMI stack trace on all CPUs arch/x86/kernel/apic/hw_nmi.c | 86 +- include/linux/percpu.h| 4 + include/linux/printk.h| 2 + include/linux/seq_buf.h | 136 kernel/printk.c | 41 +++-- lib/Makefile | 2 +- lib/seq_buf.c | 359 ++ 7 files changed, 617 insertions(+), 13 deletions(-) create mode 100644 include/linux/seq_buf.h create mode 100644 lib/seq_buf.c -- 1.8.3.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
