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2025-11-20sys_info: add a default kernel sys_info maskFeng Tang
Which serves as a global default sys_info mask. When users want the same system information for many error cases (panic, hung, lockup ...), they can chose to set this global knob only once, while not setting up each individual sys_info knobs. This just adds a 'lazy' option, and doesn't change existing kernel behavior as the mask is 0 by default. Link: https://lkml.kernel.org/r/20251113111039.22701-5-feng.tang@linux.alibaba.com Suggested-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Lance Yang <ioworker0@gmail.com> Cc: "Paul E . McKenney" <paulmck@kernel.org> Cc: Petr Mladek <pmladek@suse.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20panic: sys_info: factor out read and write handlersAndy Shevchenko
For the sake of the code readability and easier maintenance factor out read and write sys_info handlers. [akpm@linux-foundation.org: coding-style cleanups] Link: https://lkml.kernel.org/r/20251030132007.3742368-7-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Feng Tang <feng.tang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20panic: sys_info: deduplicate local variable 'table; assignmentsAndy Shevchenko
The both handlers use the local 'table' variable and assign the same data to it, deduplicate that. Link: https://lkml.kernel.org/r/20251030132007.3742368-6-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20panic: sys_info: rewrite a fix for a compilation error (`make W=1`)Andy Shevchenko
Compiler was not happy about dead variable in use: lib/sys_info.c:52:19: error: variable 'sys_info_avail' is not needed and will not be emitted [-Werror,-Wunneeded-internal-declaration] 52 | static const char sys_info_avail[] = "tasks,mem,timers,locks,ftrace,all_bt,blocked_tasks"; | ^~~~~~~~~~~~~~ This was fixed by adding __maybe_unused attribute that just hides the issue and didn't actually fix the root cause. Rewrite the fix by moving the local variable from stack to a heap. As a side effect this drops unneeded "synchronisation" of duplicative info and also makes code ready for the further refactoring. Link: https://lkml.kernel.org/r/20251030132007.3742368-5-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Feng Tang <feng.tang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20panic: sys_info:replace struct sys_info_name with plain array of stringsAndy Shevchenko
There is no need to keep a custom structure just for the need of a plain array of strings. Replace struct sys_info_name with plain array of strings. With that done, simplify the code, in particular, naturally use for_each_set_bit() when iterating over si_bits_global bitmap. Link: https://lkml.kernel.org/r/20251030132007.3742368-4-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Feng Tang <feng.tang@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20panic: sys_info: align constant definition names with parametersAndy Shevchenko
Align constant definition names with parameters to make it easier to map. It's also better to maintain and extend the names while keeping their uniqueness. Link: https://lkml.kernel.org/r/20251030132007.3742368-3-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-20panic: sys_info: capture si_bits_global before iterating over itAndy Shevchenko
Patch series "panic: sys_info: Refactor and fix a potential issue", v3. While targeting the compilation issue due to dangling variable, I have noticed more opportunities for refactoring that helps to avoid above mentioned compilation issue in a cleaner way and also fixes a potential problem with global variable access. This patch (of 6): The for-loop might re-read the content of the memory the si_bits_global points to on each iteration. Instead, just capture it for the sake of consistency and use that instead. Link: https://lkml.kernel.org/r/20251030132007.3742368-1-andriy.shevchenko@linux.intel.com Link: https://lkml.kernel.org/r/20251030132007.3742368-2-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-09-13lib/sys_info: handle sys_info_mask==0 caseFeng Tang
Generalization of panic_print's dump function [1] has been merged, and this patchset is to address some remaining issues, like adding note of the obsoletion of 'panic_print' cmdline parameter, refining the kernel document for panic_print, and hardening some string management. This patch (of 4): It is a normal case that bitmask parameter is 0, so pre-initialize the names[] to null string to cover this case. Also remove the superfluous "+1" in names[sizeof(sys_info_avail) + 1], which is needed for 'strlen()', but not for 'sizeof()'. Link: https://lkml.kernel.org/r/20250825025701.81921-1-feng.tang@linux.alibaba.com Link: https://lkml.kernel.org/r/20250825025701.81921-2-feng.tang@linux.alibaba.com Link: Link: https://lkml.kernel.org/r/20250703021004.42328-1-feng.tang@linux.alibaba.com [1] Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com> Suggested-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Cc: Askar Safin <safinaskar@zohomail.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Lance Yang <lance.yang@linux.dev> Cc: "Paul E . McKenney" <paulmck@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-19panic: add 'panic_sys_info' sysctl to take human readable string parameterFeng Tang
Bitmap definition for 'panic_print' is hard to remember and decode. Add 'panic_sys_info='sysctl to take human readable string like "tasks,mem,timers,locks,ftrace,..." and translate it into bitmap. The detailed mapping is: SYS_INFO_TASKS "tasks" SYS_INFO_MEM "mem" SYS_INFO_TIMERS "timers" SYS_INFO_LOCKS "locks" SYS_INFO_FTRACE "ftrace" SYS_INFO_ALL_CPU_BT "all_bt" SYS_INFO_BLOCKED_TASKS "blocked_tasks" [nathan@kernel.org: add __maybe_unused to sys_info_avail] Link: https://lkml.kernel.org/r/20250708-fix-clang-sys_info_avail-warning-v1-1-60d239eacd64@kernel.org Link: https://lkml.kernel.org/r/20250703021004.42328-4-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com> Suggested-by: Petr Mladek <pmladek@suse.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Lance Yang <lance.yang@linux.dev> Cc: "Paul E . McKenney" <paulmck@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-19panic: generalize panic_print's function to show sys infoFeng Tang
'panic_print' was introduced to help debugging kernel panic by dumping different kinds of system information like tasks' call stack, memory, ftrace buffer, etc. Actually this function could also be used to help debugging other cases like task-hung, soft/hard lockup, etc. where user may need the snapshot of system info at that time. Extract system info dump function related code from panic.c to separate file sys_info.[ch], for wider usage by other kernel parts for debugging. Also modify the macro names about singulars/plurals. Link: https://lkml.kernel.org/r/20250703021004.42328-3-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com> Suggested-by: Petr Mladek <pmladek@suse.com> Cc: John Ogness <john.ogness@linutronix.de> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Lance Yang <lance.yang@linux.dev> Cc: "Paul E . McKenney" <paulmck@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>