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authorNaoya Horiguchi <nao.horiguchi@gmail.com>2020-06-11 17:34:45 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-11 18:17:47 -0700
commit4e018b450ad34b0edc865e91ec5e957d677e2c4e (patch)
tree45874bd5f646a255d7fd2f15d63d271807b8c524
parent623f6dc593eaf98b91916836785278eddddaacf8 (diff)
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.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memory-failure.c20
1 files changed, 10 insertions, 10 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ababa368cb68..848de82cd547 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -402,9 +402,15 @@ static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
{
struct task_struct *t;
- for_each_thread(tsk, t)
- if ((t->flags & PF_MCE_PROCESS) && (t->flags & PF_MCE_EARLY))
- return t;
+ for_each_thread(tsk, t) {
+ if (t->flags & PF_MCE_PROCESS) {
+ if (t->flags & PF_MCE_EARLY)
+ return t;
+ } else {
+ if (sysctl_memory_failure_early_kill)
+ return t;
+ }
+ }
return NULL;
}
@@ -417,17 +423,11 @@ static struct task_struct *find_early_kill_thread(struct task_struct *tsk)
static struct task_struct *task_early_kill(struct task_struct *tsk,
int force_early)
{
- struct task_struct *t;
if (!tsk->mm)
return NULL;
if (force_early)
return tsk;
- t = find_early_kill_thread(tsk);
- if (t)
- return t;
- if (sysctl_memory_failure_early_kill)
- return tsk;
- return NULL;
+ return find_early_kill_thread(tsk);
}
/*