On Fri, Jul 23, 2021 at 1:15 AM David Hildenbrand <david@xxxxxxxxxx> wrote: > > On 23.07.21 10:11, Suren Baghdasaryan wrote: > > > > > > On Thu, Jul 22, 2021, 11:20 PM Michal Hocko <mhocko@xxxxxxxx > > <mailto:mhocko@xxxxxxxx>> wrote: > > > > On Thu 22-07-21 21:47:56, Suren Baghdasaryan wrote: > > > On Thu, Jul 22, 2021, 7:04 PM Shakeel Butt <shakeelb@xxxxxxxxxx > > <mailto:shakeelb@xxxxxxxxxx>> wrote: > > > > > > > On Thu, Jul 22, 2021 at 6:14 PM Suren Baghdasaryan > > <surenb@xxxxxxxxxx <mailto:surenb@xxxxxxxxxx>> > > > > wrote: > > > > > > > > > [...] > > > > > + > > > > > + mmap_read_lock(mm); > > > > > > > > How about mmap_read_trylock(mm) and return -EAGAIN on failure? > > > > > > > > > > That sounds like a good idea. Thanks! I'll add that in the next > > respin. > > > > Why is that a good idea? Can you do anything meaningful about the > > failure other than immediately retry the syscall and hope for the best? > > > > > > I was thinking if this syscall implements "best effort without blocking" > > approach then for a more strict usage user can simply retry. However > > retrying means issuing another syscall, so additional overhead... > > I guess such "best effort" approach would be unusual for a syscall, so > > maybe we can keep it as it is now and if such "do not block" mode is > > needed we can use flags to implement it later? > > The process is dying, so I am not sure what we are trying to optimize > here in respect to locking ... Trying not to block the caller, which is likely a system health monitoring process. However, if not blocking is important, it can issue this syscall from a separate thread... Let's scratch that "do not block" mode and keep it simple as it is now. > > > -- > Thanks, > > David / dhildenb > > -- > To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@xxxxxxxxxxx. >
