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Miller" , Dave Hansen , David Hildenbrand , Dinh Nguyen , Geert Uytterhoeven , Guo Ren , Heiko Carstens , Helge Deller , Huacai Chen , Ingo Molnar , Johannes Berg , John Paul Adrian Glaubitz , Jonathan Corbet , Klara Modin , "Liam R. Howlett" , Lorenzo Stoakes , Magnus Lindholm , Matt Turner , Max Filippov , Michael Ellerman , Michal Hocko , Michal Simek , Muchun Song , Oscar Salvador , Palmer Dabbelt , Pratyush Yadav , Richard Weinberger , Russell King , Stafford Horne , Suren Baghdasaryan , Thomas Bogendoerfer , Thomas Gleixner , Vasily Gorbik , Vineet Gupta , Vlastimil Babka , Will Deacon , x86@kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-csky@vger.kernel.org, linux-cxl@vger.kernel.org, linux-doc@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-kernel@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-openrisc@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-um@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, sparclinux@vger.kernel.org Subject: Re: [PATCH v3 24/29] arch, mm: consolidate initialization of SPARSE memory model In-Reply-To: Date: Wed, 25 Feb 2026 23:08:38 +0530 Message-ID: <87seaohgf5.ritesh.list@gmail.com> References: <20260111082105.290734-1-rppt@kernel.org> <20260111082105.290734-25-rppt@kernel.org> <87tsv5h544.ritesh.list@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Mike Rapoport writes: > Hello Ritesh, > > On Wed, Feb 25, 2026 at 09:00:35AM +0530, Ritesh Harjani wrote: >> Mike Rapoport writes: >> >> > From: "Mike Rapoport (Microsoft)" >> > >> > Every architecture calls sparse_init() during setup_arch() although the >> > data structures created by sparse_init() are not used until the >> > initialization of the core MM. >> > >> > Beside the code duplication, calling sparse_init() from architecture >> > specific code causes ordering differences of vmemmap and HVO initialization >> > on different architectures. >> > >> > Move the call to sparse_init() from architecture specific code to >> > free_area_init() to ensure that vmemmap and HVO initialization order is >> > always the same. >> > >> >> Hello Mike, >> >> [ 0.000000][ T0] ------------[ cut here ]------------ >> [ 0.000000][ T0] WARNING: arch/powerpc/include/asm/io.h:879 at virt_to_phys+0x44/0x1b8, CPU#0: swapper/0 >> [ 0.000000][ T0] Modules linked in: >> [ 0.000000][ T0] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.19.0-12139-gc57b1c00145a #31 PREEMPT >> [ 0.000000][ T0] Hardware name: IBM pSeries (emulated by qemu) POWER10 (architected) 0x801200 0xf000006 of:SLOF,git-ee03ae pSeries >> [ 0.000000][ T0] NIP: c000000000601584 LR: c000000004075de4 CTR: c000000000601548 >> [ 0.000000][ T0] REGS: c000000004d1f870 TRAP: 0700 Not tainted (6.19.0-12139-gc57b1c00145a) >> [ 0.000000][ T0] MSR: 8000000000021033 CR: 48022448 XER: 20040000 >> [ 0.000000][ T0] CFAR: c0000000006016c4 IRQMASK: 1 >> [ 0.000000][ T0] GPR00: c000000004075dd4 c000000004d1fb10 c00000000304bb00 c000000180000000 >> [ 0.000000][ T0] GPR04: 0000000000000009 0000000000000009 c000000004ec94a0 0000000000000000 >> [ 0.000000][ T0] GPR08: 0000000000018000 0000000000000001 c000000004921280 0000000048022448 >> [ 0.000000][ T0] GPR12: c000000000601548 c000000004fe0000 0000000000000004 0000000000000004 >> [ 0.000000][ T0] GPR16: 000000000287fb08 0000000000000060 0000000000000002 0000000002831750 >> [ 0.000000][ T0] GPR20: 0000000002831778 fffffffffffffffd c000000004d78050 00000000051cbb00 >> [ 0.000000][ T0] GPR24: 0000000005a40008 c000000000000000 c000000000400000 0000000000000100 >> [ 0.000000][ T0] GPR28: c000000004d78050 0000000000000000 c000000004ecd4a8 0000000000000001 >> [ 0.000000][ T0] NIP [c000000000601584] virt_to_phys+0x44/0x1b8 >> [ 0.000000][ T0] LR [c000000004075de4] alloc_bootmem+0x144/0x1a8 >> [ 0.000000][ T0] Call Trace: >> [ 0.000000][ T0] [c000000004d1fb50] [c000000004075dd4] alloc_bootmem+0x134/0x1a8 >> [ 0.000000][ T0] [c000000004d1fba0] [c000000004075fac] __alloc_bootmem_huge_page+0x164/0x230 >> [ 0.000000][ T0] [c000000004d1fbe0] [c000000004030bc4] alloc_bootmem_huge_page+0x44/0x138 >> [ 0.000000][ T0] [c000000004d1fc10] [c000000004076e48] hugetlb_hstate_alloc_pages+0x350/0x5ac >> [ 0.000000][ T0] [c000000004d1fd30] [c0000000040782f0] hugetlb_bootmem_alloc+0x15c/0x19c >> [ 0.000000][ T0] [c000000004d1fd70] [c00000000406d7b4] mm_core_init_early+0x7c/0xdf4 >> [ 0.000000][ T0] [c000000004d1ff30] [c000000004011d84] start_kernel+0xac/0xc58 >> [ 0.000000][ T0] [c000000004d1ffe0] [c00000000000e99c] start_here_common+0x1c/0x20 >> [ 0.000000][ T0] Code: 6129ffff 792907c6 6529ffff 6129ffff 7c234840 40810018 3d2201e8 3929a7a8 e9290000 7c291840 41810044 3be00001 <0b1f0000> 3d20bfff 6129ffff 792907c6 >> >> >> I think this is happening because, now in mm_core_early_init(), the >> order of initialization between hugetlb_bootmem_alloc() and >> free_area_init() is reversed. Since free_area_init() -> sparse_init() >> is responsible for setting SECTIONS and vmemmap area. >> >> Then in alloc_bootmem() (from hugetlb_bootmem_alloc() path), it uses virt_to_phys(m)... >> >> /* >> * For pre-HVO to work correctly, pages need to be on >> * the list for the node they were actually allocated >> * from. That node may be different in the case of >> * fallback by memblock_alloc_try_nid_raw. So, >> * extract the actual node first. >> */ >> if (m) >> listnode = early_pfn_to_nid(PHYS_PFN(virt_to_phys(m))); >> >> >> ... virt_to_phys on powerpc uses: >> >> static inline unsigned long virt_to_phys(const volatile void * address) >> { >> WARN_ON(IS_ENABLED(CONFIG_DEBUG_VIRTUAL) && !virt_addr_valid(address)); >> >> return __pa((unsigned long)address); >> } >> >> #define virt_addr_valid(vaddr) ({ \ >> unsigned long _addr = (unsigned long)vaddr; \ >> _addr >= PAGE_OFFSET && _addr < (unsigned long)high_memory && \ >> pfn_valid(virt_to_pfn((void *)_addr)); \ >> }) >> >> >> I think the above warning in dmesg gets printed from above WARN_ON, i.e. >> because pfn_valid() is false, since we haven't done sparse_init() yet. > > Yes, I agree. > >> So, what I wanted to check was - do you think instead of virt_to_phys(), we >> could directly use __pa() here() in mm/hugetlb.c, since these are >> memblock alloc addresses? i.e.: >> >> // alloc_bootmem(): >> - listnode = early_pfn_to_nid(PHYS_PFN(virt_to_phys(m))); >> + listnode = early_pfn_to_nid(PHYS_PFN(__pa(m))); >> >> // __alloc_bootmem_huge_page(): >> - memblock_reserved_mark_noinit(virt_to_phys((void *)m + PAGE_SIZE), >> + memblock_reserved_mark_noinit(__pa((void *)m + PAGE_SIZE), > > It surely will work for powerpc :) > I checked the definitions of __pa() on other architectures and it seems the > safest and the easiest way to fix this. > > Would you send a formal patch? > Thanks Mike for taking a look at above and confirming. Sure, let me prepare the patch and send it by tomorrow. -ritesh