user/sven/linux.git/kernel/panic.c, branch v3.18.109

printk: do cond_resched() between lines while outputting to consoles

2016-02-10T03:57:30Z

[ Upstream commit 8d91f8b15361dfb438ab6eb3b319e2ded43458ff ] @console_may_schedule tracks whether console_sem was acquired through lock or trylock. If the former, we're inside a sleepable context and console_conditional_schedule() performs cond_resched(). This allows console drivers which use console_lock for synchronization to yield while performing time-consuming operations such as scrolling. However, the actual console outputting is performed while holding irq-safe logbuf_lock, so console_unlock() clears @console_may_schedule before starting outputting lines. Also, only a few drivers call console_conditional_schedule() to begin with. This means that when a lot of lines need to be output by console_unlock(), for example on a console registration, the task doing console_unlock() may not yield for a long time on a non-preemptible kernel. If this happens with a slow console devices, for example a serial console, the outputting task may occupy the cpu for a very long time. Long enough to trigger softlockup and/or RCU stall warnings, which in turn pile more messages, sometimes enough to trigger the next cycle of warnings incapacitating the system. Fix it by making console_unlock() insert cond_resched() between lines if @console_may_schedule. Signed-off-by: Tejun Heo Reported-by: Calvin Owens Acked-by: Jan Kara Cc: Dave Jones Cc: Kyle McMartin Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

kernel/panic.c: turn off locks debug before releasing console lock

2016-02-10T03:57:28Z

[ Upstream commit 7625b3a0007decf2b135cb47ca67abc78a7b1bc1 ] Commit 08d78658f393 ("panic: release stale console lock to always get the logbuf printed out") introduced an unwanted bad unlock balance report when panic() is called directly and not from OOPS (e.g. from out_of_memory()). The difference is that in case of OOPS we disable locks debug in oops_enter() and on direct panic call nobody does that. Fixes: 08d78658f393 ("panic: release stale console lock to always get the logbuf printed out") Reported-by: kernel test robot Signed-off-by: Vitaly Kuznetsov Cc: HATAYAMA Daisuke Cc: Masami Hiramatsu Cc: Jiri Kosina Cc: Baoquan He Cc: Prarit Bhargava Cc: Xie XiuQi Cc: Seth Jennings Cc: "K. Y. Srinivasan" Cc: Jan Kara Cc: Petr Mladek Cc: Yasuaki Ishimatsu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

panic: release stale console lock to always get the logbuf printed out

2016-02-10T03:57:19Z

[ Upstream commit 08d78658f393fefaa2e6507ea052c6f8ef4002a2 ] In some cases we may end up killing the CPU holding the console lock while still having valuable data in logbuf. E.g. I'm observing the following: - A crash is happening on one CPU and console_unlock() is being called on some other. - console_unlock() tries to print out the buffer before releasing the lock and on slow console it takes time. - in the meanwhile crashing CPU does lots of printk()-s with valuable data (which go to the logbuf) and sends IPIs to all other CPUs. - console_unlock() finishes printing previous chunk and enables interrupts before trying to print out the rest, the CPU catches the IPI and never releases console lock. This is not the only possible case: in VT/fb subsystems we have many other console_lock()/console_unlock() users. Non-masked interrupts (or receiving NMI in case of extreme slowness) will have the same result. Getting the whole console buffer printed out on crash should be top priority. [akpm@linux-foundation.org: tweak comment text] Signed-off-by: Vitaly Kuznetsov Cc: HATAYAMA Daisuke Cc: Masami Hiramatsu Cc: Jiri Kosina Cc: Baoquan He Cc: Prarit Bhargava Cc: Xie XiuQi Cc: Seth Jennings Cc: "K. Y. Srinivasan" Cc: Jan Kara Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

kernel/panic.c: update comments for print_tainted

2014-11-14T00:17:06Z

Commit 69361eef9056 ("panic: add TAINT_SOFTLOCKUP") added the 'L' flag, but failed to update the comments for print_tainted(). So, update the comments. Signed-off-by: Xie XiuQi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

panic: add TAINT_SOFTLOCKUP

2014-08-08T22:57:24Z

This taint flag will be set if the system has ever entered a softlockup state. Similar to TAINT_WARN it is useful to know whether or not the system has been in a softlockup state when debugging. [akpm@linux-foundation.org: apply the taint before calling panic()] Signed-off-by: Josh Hunt Cc: Jason Baron Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/panic.c: add "crash_kexec_post_notifiers" option for kdump after panic_notifers

2014-06-06T23:08:12Z

Add a "crash_kexec_post_notifiers" boot option to run kdump after running panic_notifiers and dump kmsg. This can help rare situations where kdump fails because of unstable crashed kernel or hardware failure (memory corruption on critical data/code), or the 2nd kernel is already broken by the 1st kernel (it's a broken behavior, but who can guarantee that the "crashed" kernel works correctly?). Usage: add "crash_kexec_post_notifiers" to kernel boot option. Note that this actually increases risks of the failure of kdump. This option should be set only if you worry about the rare case of kdump failure rather than increasing the chance of success. Signed-off-by: Masami Hiramatsu Acked-by: Motohiro Kosaki Acked-by: Vivek Goyal Cc: Eric Biederman Cc: Yoshihiro YUNOMAE Cc: Satoru MORIYA Cc: Tomoki Sekiyama Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kernel/panic.c: display reason at end + pr_emerg

2014-04-07T23:36:08Z

Currently, booting without initrd specified on 80x25 screen gives a call trace followed by atkbd : Spurious ACK. Original message ("VFS: Unable to mount root fs") is not available. Of course this could happen in other situations... This patch displays panic reason after call trace which could help lot of people even if it's not the very last line on screen. Also, convert all panic.c printk(KERN_EMERG to pr_emerg( [akpm@linux-foundation.org: missed a couple of pr_ conversions] Signed-off-by: Fabian Frederick Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

2014-04-06T16:38:07Z

Pull module updates from Rusty Russell: "Nothing major: the stricter permissions checking for sysfs broke a staging driver; fix included. Greg KH said he'd take the patch but hadn't as the merge window opened, so it's included here to avoid breaking build" * tag 'modules-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: staging: fix up speakup kobject mode Use 'E' instead of 'X' for unsigned module taint flag. VERIFY_OCTAL_PERMISSIONS: stricter checking for sysfs perms. kallsyms: fix percpu vars on x86-64 with relocation. kallsyms: generalize address range checking module: LLVMLinux: Remove unused function warning from __param_check macro Fix: module signature vs tracepoints: add new TAINT_UNSIGNED_MODULE module: remove MODULE_GENERIC_TABLE module: allow multiple calls to MODULE_DEVICE_TABLE() per module module: use pr_cont

Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-03-31T21:13:25Z

Pull x86 LTO changes from Peter Anvin: "More infrastructure work in preparation for link-time optimization (LTO). Most of these changes is to make sure symbols accessed from assembly code are properly marked as visible so the linker doesn't remove them. My understanding is that the changes to support LTO are still not upstream in binutils, but are on the way there. This patchset should conclude the x86-specific changes, and remaining patches to actually enable LTO will be fed through the Kbuild tree (other than keeping up with changes to the x86 code base, of course), although not necessarily in this merge window" * 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits) Kbuild, lto: Handle basic LTO in modpost Kbuild, lto: Disable LTO for asm-offsets.c Kbuild, lto: Add a gcc-ld script to let run gcc as ld Kbuild, lto: add ld-version and ld-ifversion macros Kbuild, lto: Drop .number postfixes in modpost Kbuild, lto, workaround: Don't warn for initcall_reference in modpost lto: Disable LTO for sys_ni lto: Handle LTO common symbols in module loader lto, workaround: Add workaround for initcall reordering lto: Make asmlinkage __visible x86, lto: Disable LTO for the x86 VDSO initconst, x86: Fix initconst mistake in ts5500 code initconst: Fix initconst mistake in dcdbas asmlinkage: Make trace_hardirqs_on/off_caller visible asmlinkage, x86: Fix 32bit memcpy for LTO asmlinkage Make __stack_chk_failed and memcmp visible asmlinkage: Mark rwsem functions that can be called from assembler asmlinkage asmlinkage: Make main_extable_sort_needed visible asmlinkage, mutex: Mark __visible asmlinkage: Make trace_hardirq visible ...

Use 'E' instead of 'X' for unsigned module taint flag.

2014-03-31T04:22:43Z

Takashi Iwai says: > The letter 'X' has been already used for SUSE kernels for very long > time, to indicate the external supported modules. Can the new flag be > changed to another letter for avoiding conflict...? > (BTW, we also use 'N' for "no support", too.) Note: this code should be cleaned up, so we don't have such maps in three places! Signed-off-by: Rusty Russell