kernel.git/drivers/tty/sysrq.c, branch linux-4.13.y

oom: improve oom disable handling

2017-05-03T22:52:10Z

Tetsuo has reported that sysrq triggered OOM killer will print a misleading information when no tasks are selected: sysrq: SysRq : Manual OOM execution Out of memory: Kill process 4468 ((agetty)) score 0 or sacrifice child Killed process 4468 ((agetty)) total-vm:43704kB, anon-rss:1760kB, file-rss:0kB, shmem-rss:0kB sysrq: SysRq : Manual OOM execution Out of memory: Kill process 4469 (systemd-cgroups) score 0 or sacrifice child Killed process 4469 (systemd-cgroups) total-vm:10704kB, anon-rss:120kB, file-rss:0kB, shmem-rss:0kB sysrq: SysRq : Manual OOM execution sysrq: OOM request ignored because killer is disabled sysrq: SysRq : Manual OOM execution sysrq: OOM request ignored because killer is disabled sysrq: SysRq : Manual OOM execution sysrq: OOM request ignored because killer is disabled The real reason is that there are no eligible tasks for the OOM killer to select but since commit 7c5f64f84483 ("mm: oom: deduplicate victim selection code for memcg and global oom") the semantic of out_of_memory has changed without updating moom_callback. This patch updates moom_callback to tell that no task was eligible which is the case for both oom killer disabled and no eligible tasks. In order to help distinguish first case from the second add printk to both oom_killer_{enable,disable}. This information is useful on its own because it might help debugging potential memory allocation failures. Fixes: 7c5f64f84483 ("mm: oom: deduplicate victim selection code for memcg and global oom") Link: http://lkml.kernel.org/r/20170404134705.6361-1-mhocko@kernel.org Signed-off-by: Michal Hocko Reported-by: Tetsuo Handa Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

net: ibm: emac: remove unused sysrq handler for 'c' key

2017-04-05T14:26:18Z

Since commit d6580a9f1523 ("kexec: sysrq: simplify sysrq-c handler"), the sysrq handler for the 'c' key has been sysrq_crash_op. Debugging code in the ibm_emac driver also tries to register a handler for the 'c' key, but this has no effect because register_sysrq_key() doesn't replace existing handlers. Since evidently no one has cared enough to fix this in the last 8 years, and it's very rare for drivers to register sysrq handlers (for good reason), just remove the dead code. Signed-off-by: Eric Biggers Signed-off-by: David S. Miller

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

2017-03-02T07:42:35Z

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

2017-03-02T07:42:29Z

lib/show_mem.c: teach show_mem to work with the given nodemask

2017-02-23T00:41:30Z

show_mem() allows to filter out node specific data which is irrelevant to the allocation request via SHOW_MEM_FILTER_NODES. The filtering is done in skip_free_areas_node which skips all nodes which are not in the mems_allowed of the current process. This works most of the time as expected because the nodemask shouldn't be outside of the allocating task but there are some exceptions. E.g. memory hotplug might want to request allocations from outside of the allowed nodes (see new_node_page). Get rid of this hardcoded behavior and push the allocation mask down the show_mem path and use it instead of cpuset_current_mems_allowed. NULL nodemask is interpreted as cpuset_current_mems_allowed. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/20170117091543.25850-5-mhocko@kernel.org Signed-off-by: Michal Hocko Acked-by: Mel Gorman Cc: Hillf Danton Cc: Johannes Weiner Cc: Vlastimil Babka Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sysrq: attach sysrq handler correctly for 32-bit kernel

2017-01-11T08:22:54Z

The sysrq input handler should be attached to the input device which has a left alt key. On 32-bit kernels, some input devices which has a left alt key cannot attach sysrq handler. Because the keybit bitmap in struct input_device_id for sysrq is not correctly initialized. KEY_LEFTALT is 56 which is greater than BITS_PER_LONG on 32-bit kernels. I found this problem when using a matrix keypad device which defines a KEY_LEFTALT (56) but doesn't have a KEY_O (24 == 56%32). Cc: Jiri Slaby Signed-off-by: Akinobu Mita Acked-by: Dmitry Torokhov Cc: stable Signed-off-by: Greg Kroah-Hartman

mm: oom: add memcg to oom_control

2016-07-26T23:19:19Z

It's a part of oom context just like allocation order and nodemask, so let's move it to oom_control instead of passing it in the argument list. Link: http://lkml.kernel.org/r/40e03fd7aaf1f55c75d787128d6d17c5a71226c2.1464358556.git.vdavydov@virtuozzo.com Signed-off-by: Vladimir Davydov Acked-by: Michal Hocko Acked-by: Johannes Weiner Cc: Tetsuo Handa Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sysrq: Fix warning in sysrq generated crash.

2015-12-30T00:29:18Z

Commit 984d74a72076a1 ("sysrq: rcu-ify __handle_sysrq") replaced spin_lock_irqsave() calls with rcu_read_lock() calls in sysrq. Since rcu_read_lock() does not disable preemption, faulthandler_disabled() in __do_page_fault() in x86/fault.c returns false. When the code later calls might_sleep() in the pagefault handler, we get the following warning: BUG: sleeping function called from invalid context at ../arch/x86/mm/fault.c:1187 in_atomic(): 0, irqs_disabled(): 0, pid: 4706, name: bash Preemption disabled at:[] printk+0x48/0x4a To fix this, we release the RCU read lock before we crash. Tested this patch on linux 3.18 by booting off one of our boards. Fixes: 984d74a72076a1 ("sysrq: rcu-ify __handle_sysrq") Signed-off-by: Ani Sinha Reviewed-by: Rik van Riel Signed-off-by: Paul E. McKenney

drivers/tty: make sysrq.c slightly more explicitly non-modular

2015-10-04T16:27:56Z

The Kconfig currently controlling compilation of this code is: config.debug:config MAGIC_SYSRQ bool "Magic SysRq key" ...meaning that it currently is not being built as a module by anyone. Lets remove the traces of modularity we can so that when reading the driver there is less doubt it is builtin-only. Since module_init translates to device_initcall in the non-modular case, the init ordering remains unchanged with this commit. We don't delete the module.h include since other parts of the file are using content from there. Cc: Greg Kroah-Hartman Cc: Jiri Slaby Signed-off-by: Paul Gortmaker Signed-off-by: Greg Kroah-Hartman