On Tue, 31 May 2022 23:36:22 +0800 Chen Lin wrote: > At 2022-05-31 22:14:12, "Jakub Kicinski" <kuba@xxxxxxxxxx> wrote: > >On Tue, 31 May 2022 22:41:12 +0800 Chen Lin wrote: > >> The sample code above cannot completely solve the current problem. > >> For example, when fragsz is greater than PAGE_FRAG_CACHE_MAX_SIZE(32768), > >> __page_frag_cache_refill will return a memory of only 32768 bytes, so > >> should we continue to expand the PAGE_FRAG_CACHE_MAX_SIZE? Maybe more > >> work needs to be done > > > >Right, but I can think of two drivers off the top of my head which will > >allocate <=32k frags but none which will allocate more. > > In fact, it is rare to apply for more than one page, so is it necessary to > change it to support? I don't really care if it's supported TBH, but I dislike adding a branch to the fast path just to catch one or two esoteric bad callers. Maybe you can wrap the check with some debug CONFIG_ so it won't run on production builds? > we can just warning and return, also it is easy to synchronize this simple > protective measures to lower Linux versions.
