Messages in this thread | | | Date | Thu, 30 Mar 2017 15:59:34 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH 4.4 48/76] libceph: force GFP_NOIO for socket allocations |
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On Thu 30-03-17 15:53:35, Ilya Dryomov wrote: > On Thu, Mar 30, 2017 at 8:25 AM, Michal Hocko <mhocko@kernel.org> wrote: > > On Wed 29-03-17 16:25:18, Ilya Dryomov wrote: [...] > >> are you saying it's OK for a block > >> device to recurse back into the filesystem when doing I/O, potentially > >> generating more I/O? > > > > No, block device has to make a forward progress guarantee when > > allocating and so use mempools or other means to achieve the same. > > OK, let me put this differently. Do you agree that a block device > cannot make _any_ kind of progress guarantee if it does a GFP_KERNEL > allocation in the I/O path?
yes that is correct. And the same is correct for GFP_NOIO allocations as well. -- Michal Hocko SUSE Labs
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