On Wed 30-05-18 07:42:59, Chunyu Hu wrote: > > ----- Original Message ----- > > From: "Michal Hocko" <mhocko@xxxxxxxx> > > To: "Chunyu Hu" <chuhu@xxxxxxxxxx> > > Cc: "Tetsuo Handa" <penguin-kernel@xxxxxxxxxxxxxxxxxxx>, malat@xxxxxxxxxx, dvyukov@xxxxxxxxxx, linux-mm@xxxxxxxxx, > > "catalin marinas" <catalin.marinas@xxxxxxx> > > Sent: Wednesday, May 30, 2018 6:46:37 PM > > Subject: Re: [PATCH] kmemleak: don't use __GFP_NOFAIL > > > > On Wed 30-05-18 05:35:37, Chunyu Hu wrote: > > [...] > > > I'm trying to reuse the make_it_fail field in task for fault injection. As > > > adding > > > an extra memory alloc flag is not thought so good, I think adding task > > > flag > > > is either? > > > > Yeah, task flag will be reduced to KMEMLEAK enabled configurations > > without an additional maint. overhead. Anyway, you should really think > > about how to guarantee trackability for atomic allocation requests. You > > cannot simply assume that GFP_NOWAIT will succeed. I guess you really > > Sure. While I'm using task->make_it_fail, I'm still in the direction of > making kmemleak avoid fault inject with task flag instead of page alloc flag. > > > want to have a pre-populated pool of objects for those requests. The > > obvious question is how to balance such a pool. It ain't easy to track > > memory by allocating more memory... > > This solution is going to make kmemleak trace really nofail. We can think > later. > > while I'm thinking about if fault inject can be disabled via flag in task. > > Actually, I'm doing something like below, the disable_fault_inject() is > just setting a flag in task->make_it_fail. But this will depend on if > fault injection accept a change like this. CCing Akinobu You still seem to be missing my point I am afraid (or I am ;). So say that you want to track a GFP_NOWAIT allocation request. So create_object will get called with that gfp mask and no matter what you try here your tracking object will be allocated in a weak allocation context as well and disable kmemleak. So it only takes a more heavy memory pressure and the tracing is gone... -- Michal Hocko SUSE Labs
