Peter Zijlstra <pet...@infradead.org> writes: > On Mon, Sep 26, 2016 at 11:27:08AM +0300, Alexander Shishkin wrote: >> Peter Zijlstra <pet...@infradead.org> writes: >> > At which point we _should_ start failing fork(), which is a somewhat >> > unexpected, and undesirable side-effect. >> >> I'm not sure I see why we should fail fork() when we run out of pinned >> memory. > > Well, we cannot fully honour the inherit, what other option do we have? > Silently malfunctioning? That's far worse.
We can still put a note there saying that we tried. The user will know to adjust their buffer size requirement or the RLIMIT_MEMLOCK. >> > Ideally we'd unpin the old buffers and repin the new buffers on context >> > switch, but that's impossible since faulting needs scheduling, >> > recursion, we loose. >> >> Or we can have per-cpu buffers for all user's tasks, record where each >> task starts and ends in each buffer and cut out only bits relevant to >> the task(s) that dump core. > > Which gets you the problem that when a task dumps core there might not > be any state in the buffer, because the previous task flushed it all out > :/ Well, there's going to be at list something that leads up to the core dump if this task is the last one to schedule in for this buffer. It's a bit more gambling, though. Regards, -- Alex
