On Thu, Dec 07, 2017 at 02:20:05PM +1100, NeilBrown wrote: > We can allocate in fs/notify/fdinfo.c:show_fdinfo() which is > the earliest 'notify' specific code to run. There is no > opportunity to return an error but GFP_KERNEL allocations under 1 page > never fail.. "never" * The default allocator behavior depends on the request size. We have a concept * of so called costly allocations (with order > PAGE_ALLOC_COSTLY_ORDER). * !costly allocations are too essential to fail so they are implicitly * non-failing by default (with some exceptions like OOM victims might fail so * the caller still has to check for failures) while costly requests try to be * not disruptive and back off even without invoking the OOM killer. * The following three modifiers might be used to override some of these * implicit rules