From 1029a2b52c09e479fd7b07275812ad97868c0fb0 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 24 Sep 2014 10:18:49 +0200 Subject: sched, exit: Deal with nested sleeps do_wait() is a big wait loop, but we set TASK_RUNNING too late; we end up calling potential sleeps before we reset it. Not strictly a bug since we're guaranteed to exit the loop and not call schedule(); put in annotations to quiet might_sleep(). WARNING: CPU: 0 PID: 1 at ../kernel/sched/core.c:7123 __might_sleep+0x7e/0x90() do not call blocking ops when !TASK_RUNNING; state=1 set at [] do_wait+0x88/0x270 Call Trace: [] dump_stack+0x4e/0x7a [] warn_slowpath_common+0x8c/0xc0 [] warn_slowpath_fmt+0x4c/0x50 [] __might_sleep+0x7e/0x90 [] might_fault+0x55/0xb0 [] wait_consider_task+0x90b/0xc10 [] do_wait+0x104/0x270 [] SyS_wait4+0x77/0x100 [] system_call_fastpath+0x16/0x1b Signed-off-by: Peter Zijlstra (Intel) Cc: tglx@linutronix.de Cc: umgwanakikbuti@gmail.com Cc: ilya.dryomov@inktank.com Cc: Alex Elder Cc: Andrew Morton Cc: Axel Lin Cc: Daniel Borkmann Cc: Dave Jones Cc: Guillaume Morin Cc: Ionut Alexa Cc: Jason Baron Cc: Linus Torvalds Cc: Michal Hocko Cc: Michal Schmidt Cc: Oleg Nesterov Cc: Paul E. McKenney Cc: Rik van Riel Cc: Rusty Russell Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20140924082242.186408915@infradead.org Signed-off-by: Ingo Molnar --- include/linux/kernel.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 3d770f5564b8..5068a0d9fecd 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -175,10 +175,12 @@ extern int _cond_resched(void); */ # define might_sleep() \ do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0) +# define sched_annotate_sleep() __set_current_state(TASK_RUNNING) #else static inline void __might_sleep(const char *file, int line, int preempt_offset) { } # define might_sleep() do { might_resched(); } while (0) +# define sched_annotate_sleep() do { } while (0) #endif #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0) -- cgit v1.2.3 From 3427445afd26bd2395f29241319283a93f362cd0 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 24 Sep 2014 10:18:56 +0200 Subject: sched: Exclude cond_resched() from nested sleep test cond_resched() is a preemption point, not strictly a blocking primitive, so exclude it from the ->state test. In particular, preemption preserves task_struct::state. Signed-off-by: Peter Zijlstra (Intel) Cc: tglx@linutronix.de Cc: ilya.dryomov@inktank.com Cc: umgwanakikbuti@gmail.com Cc: oleg@redhat.com Cc: Alex Elder Cc: Andrew Morton Cc: Axel Lin Cc: Daniel Borkmann Cc: Dave Jones Cc: Jason Baron Cc: Linus Torvalds Cc: Rusty Russell Cc: Steven Rostedt Link: http://lkml.kernel.org/r/20140924082242.656559952@infradead.org Signed-off-by: Ingo Molnar --- include/linux/kernel.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 5068a0d9fecd..446d76a87ba1 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -162,6 +162,7 @@ extern int _cond_resched(void); #endif #ifdef CONFIG_DEBUG_ATOMIC_SLEEP + void ___might_sleep(const char *file, int line, int preempt_offset); void __might_sleep(const char *file, int line, int preempt_offset); /** * might_sleep - annotation for functions that can sleep @@ -177,6 +178,8 @@ extern int _cond_resched(void); do { __might_sleep(__FILE__, __LINE__, 0); might_resched(); } while (0) # define sched_annotate_sleep() __set_current_state(TASK_RUNNING) #else + static inline void ___might_sleep(const char *file, int line, + int preempt_offset) { } static inline void __might_sleep(const char *file, int line, int preempt_offset) { } # define might_sleep() do { might_resched(); } while (0) -- cgit v1.2.3 From e1c2296c3485158304bfad5a80e89078463d70c8 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Thu, 16 Oct 2014 14:59:48 -0400 Subject: tty: Move session_of_pgrp() and make static tiocspgrp() is the lone caller of session_of_pgrp(); relocate and limit to file scope. Signed-off-by: Peter Hurley Reviewed-by: Alan Cox Signed-off-by: Greg Kroah-Hartman --- include/linux/kernel.h | 3 --- 1 file changed, 3 deletions(-) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 3d770f5564b8..01bc530fbfcb 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -411,9 +411,6 @@ extern int __kernel_text_address(unsigned long addr); extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); -struct pid; -extern struct pid *session_of_pgrp(struct pid *pgrp); - unsigned long int_sqrt(unsigned long); extern void bust_spinlocks(int yes); -- cgit v1.2.3 From 9e3961a0979817c612b10b2da4f3045ec9faa779 Mon Sep 17 00:00:00 2001 From: Prarit Bhargava Date: Wed, 10 Dec 2014 15:45:50 -0800 Subject: kernel: add panic_on_warn There have been several times where I have had to rebuild a kernel to cause a panic when hitting a WARN() in the code in order to get a crash dump from a system. Sometimes this is easy to do, other times (such as in the case of a remote admin) it is not trivial to send new images to the user. A much easier method would be a switch to change the WARN() over to a panic. This makes debugging easier in that I can now test the actual image the WARN() was seen on and I do not have to engage in remote debugging. This patch adds a panic_on_warn kernel parameter and /proc/sys/kernel/panic_on_warn calls panic() in the warn_slowpath_common() path. The function will still print out the location of the warning. An example of the panic_on_warn output: The first line below is from the WARN_ON() to output the WARN_ON()'s location. After that the panic() output is displayed. WARNING: CPU: 30 PID: 11698 at /home/prarit/dummy_module/dummy-module.c:25 init_dummy+0x1f/0x30 [dummy_module]() Kernel panic - not syncing: panic_on_warn set ... CPU: 30 PID: 11698 Comm: insmod Tainted: G W OE 3.17.0+ #57 Hardware name: Intel Corporation S2600CP/S2600CP, BIOS RMLSDP.86I.00.29.D696.1311111329 11/11/2013 0000000000000000 000000008e3f87df ffff88080f093c38 ffffffff81665190 0000000000000000 ffffffff818aea3d ffff88080f093cb8 ffffffff8165e2ec ffffffff00000008 ffff88080f093cc8 ffff88080f093c68 000000008e3f87df Call Trace: [] dump_stack+0x46/0x58 [] panic+0xd0/0x204 [] ? init_dummy+0x1f/0x30 [dummy_module] [] warn_slowpath_common+0xd0/0xd0 [] ? dummy_greetings+0x40/0x40 [dummy_module] [] warn_slowpath_null+0x1a/0x20 [] init_dummy+0x1f/0x30 [dummy_module] [] do_one_initcall+0xd4/0x210 [] ? __vunmap+0xc2/0x110 [] load_module+0x16a9/0x1b30 [] ? store_uevent+0x70/0x70 [] ? copy_module_from_fd.isra.44+0x129/0x180 [] SyS_finit_module+0xa6/0xd0 [] system_call_fastpath+0x12/0x17 Successfully tested by me. hpa said: There is another very valid use for this: many operators would rather a machine shuts down than being potentially compromised either functionally or security-wise. Signed-off-by: Prarit Bhargava Cc: Jonathan Corbet Cc: Rusty Russell Cc: "H. Peter Anvin" Cc: Andi Kleen Cc: Masami Hiramatsu Acked-by: Yasuaki Ishimatsu Cc: Fabian Frederick Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kernel.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/kernel.h') diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 446d76a87ba1..233ea8107038 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -427,6 +427,7 @@ extern int panic_timeout; extern int panic_on_oops; extern int panic_on_unrecovered_nmi; extern int panic_on_io_nmi; +extern int panic_on_warn; extern int sysctl_panic_on_stackoverflow; /* * Only to be used by arch init code. If the user over-wrote the default -- cgit v1.2.3