On Thu, Nov 04, 2021 at 01:57:03PM -0400, Qian Cai wrote: > On 11/4/21 1:06 PM, Mike Rapoport wrote: > > I think I'll be better to rename MEMBLOCK_ALLOC_KASAN to, say, > > MEMBLOCK_ALLOC_NOKMEMLEAK and use that for both KASAN and page table cases. > > Okay, that would look a bit nicer. Or MEMBLOCK_ALLOC_ACCESSIBLE_NOLEAKTRACE to match SLAB_NOLEAKTRACE and also hint that it's accessible memory. > > But more generally, we are going to hit this again and again. > > Couldn't we add a memblock allocation as a mean to get more memory to > > kmemleak::mem_pool_alloc()? > > For the last 5 years, this is the second time I am ware of this kind of > issue just because of the 64KB->4KB switch on those servers, although I > agree it could happen again in the future due to some new debugging > features etc. I don't feel a strong need to rewrite it now though. Not > sure if Catalin saw things differently. Anyway, Mike, do you agree that > we could rewrite that separately in the future? I was talking to Mike on IRC last night and I think you still need a flag, otherwise you could get a recursive memblock -> kmemleak -> memblock call (that's why we have SLAB_NOLEAKTRACE). So for the time being, a new MEMBLOCK_* definition would do. I wonder whether we could actually use the bottom bits in the end/limit as actual flags so one can do (MEMBLOCK_ALLOC_ACCESSIBLE | MEMBLOCK_NOLEAKTRACE). But that could be for a separate clean-up. -- Catalin
