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authorEric W. Biederman <ebiederm@xmission.com>2022-05-11 12:16:21 -0500
committerEric W. Biederman <ebiederm@xmission.com>2022-05-11 12:41:48 -0500
commitb3f9916d81e8ffb21cbe7abccf63f86a5a1d598a (patch)
tree1cc0cb57ee6ae02300d86f0325a7bff50dfae479 /kernel
parent1b2552cbdbe099b51aaffa486c042b0a7bf0a808 (diff)
sched: Update task_tick_numa to ignore tasks without an mm
Qian Cai <quic_qiancai@quicinc.com> wrote: > Reverting the last 3 commits of the series fixed a boot crash. > > 1b2552cbdbe0 fork: Stop allowing kthreads to call execve > 753550eb0ce1 fork: Explicitly set PF_KTHREAD > 68d85f0a33b0 init: Deal with the init process being a user mode process > > BUG: KASAN: null-ptr-deref in task_nr_scan_windows.isra.0 > arch_atomic_long_read at ./include/linux/atomic/atomic-long.h:29 > (inlined by) atomic_long_read at ./include/linux/atomic/atomic-instrumented.h:1266 > (inlined by) get_mm_counter at ./include/linux/mm.h:1996 > (inlined by) get_mm_rss at ./include/linux/mm.h:2049 > (inlined by) task_nr_scan_windows at kernel/sched/fair.c:1123 > Read of size 8 at addr 00000000000003d0 by task swapper/0/1 With the change to init and the user mode helper processes to not have PF_KTHREAD set before they call kernel_execve the PF_KTHREAD test in task_tick_numa became insufficient to detect all tasks that have "->mm == NULL". Correct that by testing for "->mm == NULL" directly. Reported-by: Qian Cai <quic_qiancai@quicinc.com> Tested-by: Qian Cai <quic_qiancai@quicinc.com> Fixes: 1b2552cbdbe0 ("fork: Stop allowing kthreads to call execve") Link: https://lkml.kernel.org/r/87r150ug1l.fsf_-_@email.froward.int.ebiederm.org Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/fair.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d4bd299d67ab..db6f0df9d43e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2915,7 +2915,7 @@ static void task_tick_numa(struct rq *rq, struct task_struct *curr)
/*
* We don't care about NUMA placement if we don't have memory.
*/
- if ((curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work)
+ if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work)
return;
/*