On Wed, Nov 22, 2023 at 10:29:00AM -0800, Andrew Morton wrote: > On Wed, 22 Nov 2023 21:23:58 +0300 Serge Semin <fancer.lancer@xxxxxxxxx> wrote: > > > Just recently I've rebased my MIPS32-related work from kernel 6.5-rc4 onto > > the latest kernel 6.7-rc1 and immediately got into a bootup-time > > mm-related bug (see patches 3-5 in this series). After fixing it I decided > > it was time to submit for review the generic MIPS code fixes which I have > > been collecting in my local repo for the last year. I was going to submit > > them a bit later after I finished working on a patchset with my SoC > > arch-specific changes, but since it was getting bigger and bigger, it > > turned to be reasonable to spill out the generic part of series right away > > especially seeing it might get to be useful in the most recent kernel. > > It would have been better to separate out the two tiny unrelated MM > patches from this series. One of them isn't completely unrelated to the series content. The biggest problem I fixed in the patch [PATCH 3/7] mips: Fix max_mapnr being uninitialized on early stages Link: https://lore.kernel.org/linux-mips/20231122182419.30633-4-fancer.lancer@xxxxxxxxx/ of this series. I was sure that it was a correct fix at least for having the pfn_valid() method working incorrectly, but I had doubts whether the memory mapped IO pages were supposed to be left uninitialized by the arch code relying on the init_unavailable_range() doing that especially seeing it was printing a warning about having unavailable ranges. If it turned out to be incorrect I would have needed to drop the patch [PATCH 5/7] mm/mm_init.c: Extend init unavailable range doc info Link: https://lore.kernel.org/linux-mips/20231122182419.30633-6-fancer.lancer@xxxxxxxxx/ and fix that problem too in the framework of the MIPS arch. My alternative assumption regarding that problem was that the arch-code should have used memblock_reserve() method for the IO ranges, so then the calls-chain: mem_init() +-> memblock_free_all() +-> free_low_memory_core_early() +-> memmap_init_reserved_pages() +-> memmap_init_reserved_pages(v) +-> for_each_reserved_mem_region(region) +-> reserve_bootmem_region(start, end, nid); would have properly initialized the IO-pages reserved earlier by means of the memblock_reserve() method. But it turned out that reserve_bootmem_region() was available only when CONFIG_DEFERRED_STRUCT_PAGE_INIT was enabled which didn't seem to be widespreadly utilized in the arch code. Not finding a better option I decided to stick to the solution relying on the init_unavailable_range() method doing the trick and just fix the method kdoc. Seeing you accepted the patch [PATCH 5/7] mm/mm_init.c: Extend init unavailable range doc info it was a correct decision. > I'll steal them - if they later turn up via > the MIPS tree then that's OK. Ok. Thanks for picking them up. I'll drop those two patches from the series on v2. -Serge(y)
