mm/memory-failure: prioritize prctl(PR_MCE_KILL) over vm.memory_failure_early_kill
Patch series "hwpoison: fixes signaling on memory error" This is a small patchset to solve issues in memory error handler to send SIGBUS to proper process/thread as expected in configuration. Please see descriptions in individual patches for more details. This patch (of 2): Early-kill policy is controlled from two types of settings, one is per-process setting prctl(PR_MCE_KILL) and the other is system-wide setting vm.memory_failure_early_kill. Users expect per-process setting to override system-wide setting as many other settings do, but early-kill setting doesn't work as such. For example, if a system configures vm.memory_failure_early_kill to 1 (enabled), a process receives SIGBUS even if it's configured to explicitly disable PF_MCE_KILL by prctl(). That's not desirable for applications with their own policies. This patch is suggesting to change the priority of these two types of settings, by checking sysctl_memory_failure_early_kill only when a given process has the default kill policy. Note that this patch is solving a thread choice issue too. Originally, collect_procs() always chooses the main thread when vm.memory_failure_early_kill is 1, even if the process has a dedicated thread for memory error handling. SIGBUS should be sent to the dedicated thread if early-kill is enabled via vm.memory_failure_early_kill as we are doing for PR_MCE_KILL_EARLY processes. Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Link: http://lkml.kernel.org/r/1591321039-22141-1-git-send-email-naoya.horiguchi@nec.com Link: http://lkml.kernel.org/r/1591321039-22141-2-git-send-email-naoya.horiguchi@nec.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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