David Hildenbrand
2023-Jun-27 13:28 UTC
[PATCH v1 1/5] mm/memory_hotplug: check for fatal signals only in offline_pages()
On 27.06.23 14:34, Michal Hocko wrote:> On Tue 27-06-23 13:22:16, David Hildenbrand wrote: >> Let's check for fatal signals only. That looks cleaner and still keeps >> the documented use case for manual user-space triggered memory offlining >> working. From Documentation/admin-guide/mm/memory-hotplug.rst: >> >> % timeout $TIMEOUT offline_block | failure_handling >> >> In fact, we even document there: "the offlining context can be terminated >> by sending a fatal signal". > > We should be fixing documentation instead. This could break users who do > have a SIGALRM signal hander installed.You mean because timeout will send a SIGALRM, which is not considered fatal in case a signal handler is installed? At least the "traditional" tools I am aware of don't set a timeout at all (crossing fingers that they never end up stuck): * chmem * QEMU guest agent * powerpc-utils libdaxctl also doesn't seem to implement an easy-to-spot timeout for memory offlining, but it also doesn't configure SIGALRM. Of course, that doesn't mean that there isn't somewhere a program that does that; I merely assume that it would be pretty unlikely to find such a program. But no strong opinion: we can also keep it like that, update the doc and add a comment why this one here is different than most other signal backoff checks. Thanks! -- Cheers, David / dhildenb