On 9/10/21 4:04 PM, Tetsuo Handa wrote: > On 2021/09/10 21:39, Vasily Averin wrote: >> The kernel currently allows dying tasks to exceed the memcg limits. >> The allocation is expected to be the last one and the occupied memory >> will be freed soon. >> This is not always true because it can be part of the huge vmalloc >> allocation. Allowed once, they will repeat over and over again. >> Moreover lifetime of the allocated object can differ from >> In addition the lifetime of the dying task. > > Can't we add fatal_signal_pending(current) test to vmalloc() loop? 1) this has been done in the past but has been reverted later. 2) any vmalloc changes will affect non-memcg allocations too. If we're doing memcg-related checks it's better to do it in one place. 3) it is not vmalloc-only issue. Huge number of kmalloc page allocations from N concurrent threads will lead to the same problem. >> Multiple such allocations running concurrently can not only overuse >> the memcg limit, but can lead to a global out of memory and, >> in the worst case, cause the host to panic. >> >> Signed-off-by: Vasily Averin <vvs@xxxxxxxxxxxxx>
