Since the 2.6 kernel, the oom killer has slightly biased away from
CAP_SYS_ADMIN processes by discounting some of its memory usage in
comparison to other processes.
This has always been implicit and nothing exactly relies on the behavior.
Gaurav notices that __task_cred() can dereference a potentially freed
pointer if the task under consideration is exiting because a reference to
the task_struct is not held.
Remove the CAP_SYS_ADMIN bias so that all processes are treated equally.
If any CAP_SYS_ADMIN process would like to be biased against, it is always
allowed to adjust /proc/pid/oom_score_adj.
Reported-by: Gaurav Kohli <gko...@codeaurora.org>
Signed-off-by: David Rientjes <rient...@google.com>
mm/oom_kill.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
@@ -224,13 +224,6 @@ unsigned long oom_badness(struct task_struct *p, struct
mm_pgtables_bytes(p->mm) / PAGE_SIZE;
- * Root processes get 3% bonus, just like the __vm_enough_memory()
- * implementation used by LSMs.
- if (has_capability_noaudit(p, CAP_SYS_ADMIN))
- points -= (points * 3) / 100;
/* Normalize to oom_score_adj units */
adj *= totalpages / 1000;
points += adj;