On Fri, Apr 15, 2022 at 06:42:27PM -0700, Luis Chamberlain wrote: > On Fri, Apr 15, 2022 at 06:34:16PM -0700, Song Liu wrote: > > On Fri, Apr 15, 2022 at 12:05 PM Luis Chamberlain <mcgrof@xxxxxxxxxx> wrote: > > > > > > On Fri, Apr 15, 2022 at 09:44:09AM -0700, Song Liu wrote: > > > > Changes v3 => v4: > > > > 1. Fix __weak module_alloc_huge; remove unused vmalloc_huge; rename > > > > __vmalloc_huge => vmalloc_huge. (Christoph Hellwig) > > > > 2. Use vzalloc (as it was before vmalloc_no_huge) and clean up comments in > > > > kvm_s390_pv_alloc_vm. > > > > > > > > Changes v2 => v3: > > > > 1. Use __vmalloc_huge in alloc_large_system_hash. > > > > 2. Use EXPORT_SYMBOL_GPL for new functions. (Christoph Hellwig) > > > > 3. Add more description about the issues and changes.(Christoph Hellwig, > > > > Rick Edgecombe). > > > > > > > > Changes v1 => v2: > > > > 1. Add vmalloc_huge(). (Christoph Hellwig) > > > > 2. Add module_alloc_huge(). (Christoph Hellwig) > > > > 3. Add Fixes tag and Link tag. (Thorsten Leemhuis) > > > > > > > > Enabling HAVE_ARCH_HUGE_VMALLOC on x86_64 and use it for bpf_prog_pack has > > > > caused some issues [1], as many users of vmalloc are not yet ready to > > > > handle huge pages. To enable a more smooth transition to use huge page > > > > backed vmalloc memory, this set replaces VM_NO_HUGE_VMAP flag with an new > > > > opt-in flag, VM_ALLOW_HUGE_VMAP. More discussions about this topic can be > > > > found at [2]. > > > > > > > > Patch 1 removes VM_NO_HUGE_VMAP and adds VM_ALLOW_HUGE_VMAP. > > > > Patch 2 uses VM_ALLOW_HUGE_VMAP in bpf_prog_pack. > > > > > > > > [1] https://lore.kernel.org/lkml/20220204185742.271030-1-song@xxxxxxxxxx/ > > > > [2] https://lore.kernel.org/linux-mm/20220330225642.1163897-1-song@xxxxxxxxxx/ > > > > > > Looks good except for that I think this should just wait for v5.19. The > > > fixes are so large I can't see why this needs to be rushed in other than > > > the first assumptions of the optimizations had some flaws addressed here. > > > > We need these changes to fix issues like [3]. Note that there might > > still be some > > undiscovered issues with huge page backed vmalloc memory on powerpc, which > > had HAVE_ARCH_HUGE_VMALLOC enabled since the 5.15 kernel. As we > > agreed, the new opt-in flag is a safer approach here. We probably should have > > 1/4 and 2/4 back ported to stable. Therefore, I think shipping this > > set now would > > give us a more reliable 5.18 release. > > > > Does this make sense? > > Yes absolutely, but that sounds like that optimization should just be > reverted completely from v5.18 isntead then no? Or if one can skip the > optimizations for v5.18 with a small patch, and then enable for v5.19. In any case it is up to Linus, I already chimed in with my opinion. Luis
