Thanks for taking a look! On Fri, Aug 21, 2020 at 8:51 PM Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > Why change all existing callsites so that one callsite can pass in a > different gfp_t? My initial thought was to change strndup_user to use GFP_KERNEL_ACCOUNT (or GFP_USER | __GFP_ACCOUNT ?) unconditionally. (Would that work? that would be a simpler change for sure) In the case it was not wanted, I assumed a good proportion of callers might do the same on a case-by-case basis (esp. with regards to enabling accounting). > Also... > > why does strndup_user() use GFP_USER? Nobody will be mapping the > resulting strings into user pagetables (will they?). This was done by > Al's 6c2c97a24f096e32, which doesn't have a changelog :( FWIW, I believe related to this: https://lkml.org/lkml/2018/1/6/333 It's a bit over my head (is GFP_USER cheaper?) if strndup_user needs to follow memdup_user > In [patch 2/2], > > + desc = strndup_user(user_desc, SK_MAX_DESC_SIZE, GFP_KERNEL_ACCOUNT); > > if GFP_USER is legit then shouldn't this be GFP_USER_ACCOUNT (ie, > GFP_USER|__GFP_ACCOUNT)? Yes! I'll see clearer if I manage to wrap my head around what strndup_user should do Thanks!
