From 1b04fa9900263b4e217ca2509fd778b32c2b4eb2 Mon Sep 17 00:00:00 2001 From: "Uladzislau Rezki (Sony)" Date: Wed, 9 Dec 2020 21:27:31 +0100 Subject: rcu-tasks: Move RCU-tasks initialization to before early_initcall() PowerPC testing encountered boot failures due to RCU Tasks not being fully initialized until core_initcall() time. This commit therefore initializes RCU Tasks (along with Rude RCU and RCU Tasks Trace) just before early_initcall() time, thus allowing waiting on RCU Tasks grace periods from early_initcall() handlers. Link: https://lore.kernel.org/rcu/87eekfh80a.fsf@dja-thinkpad.axtens.net/ Fixes: 36dadef23fcc ("kprobes: Init kprobes in early_initcall") Tested-by: Daniel Axtens Signed-off-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney --- init/main.c | 1 + 1 file changed, 1 insertion(+) (limited to 'init') diff --git a/init/main.c b/init/main.c index 32b2a8affafd..9d964511fe0c 100644 --- a/init/main.c +++ b/init/main.c @@ -1512,6 +1512,7 @@ static noinline void __init kernel_init_freeable(void) init_mm_internals(); + rcu_init_tasks_generic(); do_pre_smp_initcalls(); lockup_detector_init(); -- cgit v1.2.3 From a91bd6223ecd46addc71ee6fcd432206d39365d2 Mon Sep 17 00:00:00 2001 From: Petr Mladek Date: Fri, 8 Jan 2021 12:48:47 +0100 Subject: Revert "init/console: Use ttynull as a fallback when there is no console" This reverts commit 757055ae8dedf5333af17b3b5b4b70ba9bc9da4e. The commit caused that ttynull was used as the default console on several systems[1][2][3]. As a result, the console was blank even when a better alternative existed. It happened when there was no console configured on the command line and ttynull_init() was the first initcall calling register_console(). Or it happened when /dev/ did not exist when console_on_rootfs() was called. It was not able to open /dev/console even though a console driver was registered. It tried to add ttynull console but it obviously did not help. But ttynull became the preferred console and was used by /dev/console when it was available later. The commit tried to fix a historical problem that have been there for ages. The primary motivation was the commit 3cffa06aeef7ece30f6 ("printk/console: Allow to disable console output by using console="" or console=null"). It provided a clean solution for a workaround that was widely used and worked only by chance. This revert causes that the console="" or console=null command line options will again work only by chance. These options will cause that a particular console will be preferred and the default (tty) ones will not get enabled. There will be no console registered at all. As a result there won't be stdin, stdout, and stderr for the init process. But it worked exactly this way even before. The proper solution has to fulfill many conditions: + Register ttynull only when explicitly required or as the ultimate fallback. + ttynull should get associated with /dev/console but it must not become preferred console when used as a fallback. Especially, it must still be possible to replace it by a better console later. Such a change requires clean up of the register_console() code. Otherwise, it would be even harder to follow. Especially, the use of has_preferred_console and CON_CONSDEV flag is tricky. The clean up is risky. The ordering of consoles is not well defined. And any changes tend to break existing user settings. Do the revert at the least risky solution for now. [1] https://lore.kernel.org/linux-kselftest/20201221144302.GR4077@smile.fi.intel.com/ [2] https://lore.kernel.org/lkml/d2a3b3c0-e548-7dd1-730f-59bc5c04e191@synopsys.com/ [3] https://patchwork.ozlabs.org/project/linux-um/patch/20210105120128.10854-1-thomas@m3y3r.de/ Reported-by: Andy Shevchenko Reported-by: Vineet Gupta Reported-by: Thomas Meyer Signed-off-by: Petr Mladek Acked-by: Greg Kroah-Hartman Acked-by: Sergey Senozhatsky Signed-off-by: Linus Torvalds --- init/main.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'init') diff --git a/init/main.c b/init/main.c index 421640fca375..c68d784376ca 100644 --- a/init/main.c +++ b/init/main.c @@ -1480,14 +1480,8 @@ void __init console_on_rootfs(void) struct file *file = filp_open("/dev/console", O_RDWR, 0); if (IS_ERR(file)) { - pr_err("Warning: unable to open an initial console. Fallback to ttynull.\n"); - register_ttynull_console(); - - file = filp_open("/dev/console", O_RDWR, 0); - if (IS_ERR(file)) { - pr_err("Warning: Failed to add ttynull console. No stdin, stdout, and stderr for the init process!\n"); - return; - } + pr_err("Warning: unable to open an initial console.\n"); + return; } init_dup(file); init_dup(file); -- cgit v1.2.3 From 7e0a9220467dbcfdc5bc62825724f3e52e50ab31 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Fri, 29 Jan 2021 10:13:53 -0500 Subject: fgraph: Initialize tracing_graph_pause at task creation On some archs, the idle task can call into cpu_suspend(). The cpu_suspend() will disable or pause function graph tracing, as there's some paths in bringing down the CPU that can have issues with its return address being modified. The task_struct structure has a "tracing_graph_pause" atomic counter, that when set to something other than zero, the function graph tracer will not modify the return address. The problem is that the tracing_graph_pause counter is initialized when the function graph tracer is enabled. This can corrupt the counter for the idle task if it is suspended in these architectures. CPU 1 CPU 2 ----- ----- do_idle() cpu_suspend() pause_graph_tracing() task_struct->tracing_graph_pause++ (0 -> 1) start_graph_tracing() for_each_online_cpu(cpu) { ftrace_graph_init_idle_task(cpu) task-struct->tracing_graph_pause = 0 (1 -> 0) unpause_graph_tracing() task_struct->tracing_graph_pause-- (0 -> -1) The above should have gone from 1 to zero, and enabled function graph tracing again. But instead, it is set to -1, which keeps it disabled. There's no reason that the field tracing_graph_pause on the task_struct can not be initialized at boot up. Cc: stable@vger.kernel.org Fixes: 380c4b1411ccd ("tracing/function-graph-tracer: append the tracing_graph_flag") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211339 Reported-by: pierre.gondois@arm.com Signed-off-by: Steven Rostedt (VMware) --- init/init_task.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'init') diff --git a/init/init_task.c b/init/init_task.c index 8a992d73e6fb..3711cdaafed2 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -198,7 +198,8 @@ struct task_struct init_task .lockdep_recursion = 0, #endif #ifdef CONFIG_FUNCTION_GRAPH_TRACER - .ret_stack = NULL, + .ret_stack = NULL, + .tracing_graph_pause = ATOMIC_INIT(0), #endif #if defined(CONFIG_TRACING) && defined(CONFIG_PREEMPTION) .trace_recursion = 0, -- cgit v1.2.3 From 55b6f763d8bcb5546997933105d66d3e6b080e6a Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 4 Feb 2021 18:32:28 -0800 Subject: init/gcov: allow CONFIG_CONSTRUCTORS on UML to fix module gcov On ARCH=um, loading a module doesn't result in its constructors getting called, which breaks module gcov since the debugfs files are never registered. On the other hand, in-kernel constructors have already been called by the dynamic linker, so we can't call them again. Get out of this conundrum by allowing CONFIG_CONSTRUCTORS to be selected, but avoiding the in-kernel constructor calls. Also remove the "if !UML" from GCOV selecting CONSTRUCTORS now, since we really do want CONSTRUCTORS, just not kernel binary ones. Link: https://lkml.kernel.org/r/20210120172041.c246a2cac2fb.I1358f584b76f1898373adfed77f4462c8705b736@changeid Signed-off-by: Johannes Berg Reviewed-by: Peter Oberparleiter Cc: Arnd Bergmann Cc: Jessica Yu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- init/Kconfig | 1 - init/main.c | 8 +++++++- 2 files changed, 7 insertions(+), 2 deletions(-) (limited to 'init') diff --git a/init/Kconfig b/init/Kconfig index b77c60f8b963..29ad68325028 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -76,7 +76,6 @@ config CC_HAS_ASM_INLINE config CONSTRUCTORS bool - depends on !UML config IRQ_WORK bool diff --git a/init/main.c b/init/main.c index c68d784376ca..a626e78dbf06 100644 --- a/init/main.c +++ b/init/main.c @@ -1066,7 +1066,13 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) /* Call all constructor functions linked into the kernel. */ static void __init do_ctors(void) { -#ifdef CONFIG_CONSTRUCTORS +/* + * For UML, the constructors have already been called by the + * normal setup code as it's just a normal ELF binary, so we + * cannot do it again - but we do need CONFIG_CONSTRUCTORS + * even on UML for modules. + */ +#if defined(CONFIG_CONSTRUCTORS) && !defined(CONFIG_UML) ctor_fn_t *fn = (ctor_fn_t *) __ctors_start; for (; fn < (ctor_fn_t *) __ctors_end; fn++) -- cgit v1.2.3