user/sven/linux.git/kernel/debug, branch v4.14.57

kdb: make "mdr" command repeat

2018-05-30T05:52:41Z

[ Upstream commit 1e0ce03bf142454f38a5fc050bf4fd698d2d36d8 ] The "mdr" command should repeat (continue) when only Enter/Return is pressed, so make it do so. Signed-off-by: Randy Dunlap Cc: Daniel Thompson Cc: Jason Wessel Cc: kgdb-bugreport@lists.sourceforge.net Signed-off-by: Jason Wessel Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

kdb: Fix handling of kallsyms_symbol_next() return value

2017-12-14T08:52:58Z

commit c07d35338081d107e57cf37572d8cc931a8e32e2 upstream. kallsyms_symbol_next() returns a boolean (true on success). Currently kdb_read() tests the return value with an inequality that unconditionally evaluates to true. This is fixed in the obvious way and, since the conditional branch is supposed to be unreachable, we also add a WARN_ON(). Reported-by: Dan Carpenter Signed-off-by: Daniel Thompson Signed-off-by: Jason Wessel Signed-off-by: Greg Kroah-Hartman

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:34Z

We are going to split out of , which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:34Z

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:30Z

We are going to move softlockup APIs out of , which will have to be picked up from other headers and a couple of .c files. already includes . Include the header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:29Z

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:27Z

We are going to split out of , which will have to be picked up from a couple of .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

mm/vmacache, sched/headers: Introduce 'struct vmacache' and move it from to

2017-03-02T07:42:25Z

The header includes various vmacache related defines, which are arguably misplaced. Move them to mm_types.h and minimize the sched.h impact by putting all task vmacache state into a new 'struct vmacache' structure. No change in functionality. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

kdb: call vkdb_printf() from vprintk_default() only when wanted

2016-12-15T00:04:08Z

kdb_trap_printk allows to pass normal printk() messages to kdb via vkdb_printk(). For example, it is used to get backtrace using the classic show_stack(), see kdb_show_stack(). vkdb_printf() tries to avoid a potential infinite loop by disabling the trap. But this approach is racy, for example: CPU1 CPU2 vkdb_printf() // assume that kdb_trap_printk == 0 saved_trap_printk = kdb_trap_printk; kdb_trap_printk = 0; kdb_show_stack() kdb_trap_printk++; Problem1: Now, a nested printk() on CPU0 calls vkdb_printf() even when it should have been disabled. It will not cause a deadlock but... // using the outdated saved value: 0 kdb_trap_printk = saved_trap_printk; kdb_trap_printk--; Problem2: Now, kdb_trap_printk == -1 and will stay like this. It means that all messages will get passed to kdb from now on. This patch removes the racy saved_trap_printk handling. Instead, the recursion is prevented by a check for the locked CPU. The solution is still kind of racy. A non-related printk(), from another process, might get trapped by vkdb_printf(). And the wanted printk() might not get trapped because kdb_printf_cpu is assigned. But this problem existed even with the original code. A proper solution would be to get_cpu() before setting kdb_trap_printk and trap messages only from this CPU. I am not sure if it is worth the effort, though. In fact, the race is very theoretical. When kdb is running any of the commands that use kdb_trap_printk there is a single active CPU and the other CPUs should be in a holding pen inside kgdb_cpu_enter(). The only time this is violated is when there is a timeout waiting for the other CPUs to report to the holding pen. Finally, note that the situation is a bit schizophrenic. vkdb_printf() explicitly allows recursion but only from KDB code that calls kdb_printf() directly. On the other hand, the generic printk() recursion is not allowed because it might cause an infinite loop. This is why we could not hide the decision inside vkdb_printf() easily. Link: http://lkml.kernel.org/r/1480412276-16690-4-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek Cc: Daniel Thompson Cc: Jason Wessel Cc: Peter Zijlstra Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

kdb: properly synchronize vkdb_printf() calls with other CPUs

2016-12-15T00:04:08Z

kdb_printf_lock does not prevent other CPUs from entering the critical section because it is ignored when KDB_STATE_PRINTF_LOCK is set. The problematic situation might look like: CPU0 CPU1 vkdb_printf() if (!KDB_STATE(PRINTF_LOCK)) KDB_STATE_SET(PRINTF_LOCK); spin_lock_irqsave(&kdb_printf_lock, flags); vkdb_printf() if (!KDB_STATE(PRINTF_LOCK)) BANG: The PRINTF_LOCK state is set and CPU1 is entering the critical section without spinning on the lock. The problem is that the code tries to implement locking using two state variables that are not handled atomically. Well, we need a custom locking because we want to allow reentering the critical section on the very same CPU. Let's use solution from Petr Zijlstra that was proposed for a similar scenario, see https://lkml.kernel.org/r/20161018171513.734367391@infradead.org This patch uses the same trick with cmpxchg(). The only difference is that we want to handle only recursion from the same context and therefore we disable interrupts. In addition, KDB_STATE_PRINTF_LOCK is removed. In fact, we are not able to set it a non-racy way. Link: http://lkml.kernel.org/r/1480412276-16690-3-git-send-email-pmladek@suse.com Signed-off-by: Petr Mladek Reviewed-by: Daniel Thompson Cc: Jason Wessel Cc: Peter Zijlstra Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds