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[70.77.200.158]) by smtp.gmail.com with ESMTPSA id h17-20020a62b411000000b006edd05e3751sm159808pfn.176.2024.04.17.15.10.39 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Apr 2024 15:10:40 -0700 (PDT) From: Andreas Dilger Message-Id: <1F07FFF3-663B-43D4-A9DA-C89856F2962A@dilger.ca> Content-Type: multipart/signed; boundary="Apple-Mail=_B97920C0-75B2-43B7-A029-2F2368082F1C"; protocol="application/pgp-signature"; micalg=pgp-sha256 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: riscv32 EXT4 splat, 6.8 regression? Date: Wed, 17 Apr 2024 16:09:23 -0600 In-Reply-To: <20240417003639.13bfd801@namcao> Cc: Mike Rapoport , Matthew Wilcox , =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , Christian Brauner , Al Viro , linux-fsdevel , Jan Kara , Linux Kernel Mailing List , linux-riscv@lists.infradead.org, Theodore Ts'o , Ext4 Developers List , Conor Dooley , Anders Roxell , Alexandre Ghiti To: Nam Cao References: <20240416-deppen-gasleitung-8098fcfd6bbd@brauner> <8734rlo9j7.fsf@all.your.base.are.belong.to.us> <20240416171713.7d76fe7d@namcao> <20240416173030.257f0807@namcao> <87v84h2tee.fsf@all.your.base.are.belong.to.us> <20240416181944.23af44ee@namcao> <20240417003639.13bfd801@namcao> X-Mailer: Apple Mail (2.3273) --Apple-Mail=_B97920C0-75B2-43B7-A029-2F2368082F1C Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii On Apr 16, 2024, at 4:36 PM, Nam Cao wrote: > > On 2024-04-16 Mike Rapoport wrote: >> On Tue, Apr 16, 2024 at 06:00:29PM +0100, Matthew Wilcox wrote: >>> On Tue, Apr 16, 2024 at 07:31:54PM +0300, Mike Rapoport wrote: >>>>> - if (!IS_ENABLED(CONFIG_64BIT)) { >>>>> - max_mapped_addr = __pa(~(ulong)0); >>>>> - if (max_mapped_addr == (phys_ram_end - 1)) >>>>> - memblock_set_current_limit(max_mapped_addr - 4096); >>>>> - } >>>>> + memblock_reserve(__pa(-PAGE_SIZE), PAGE_SIZE); >>>> >>>> Ack. >>> >>> Can this go to generic code instead of letting architecture maintainers >>> fall over it? >> >> Yes, it's just have to happen before setup_arch() where most architectures >> enable memblock allocations. > > This also works, the reported problem disappears. > > However, I am confused about one thing: doesn't this make one page of > physical memory inaccessible? > > Is it better to solve this by setting max_low_pfn instead? Then at > least the page is still accessible as high memory. Is that one page of memory really worthwhile to preserve? Better to have a simple solution that works, maybe even mapping that page read-only so that any code which tries to dereference an ERR_PTR address immediately gets a fault? Cheers, Andreas > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > index fa34cf55037b..6e3130cae675 100644 > --- a/arch/riscv/mm/init.c > +++ b/arch/riscv/mm/init.c > @@ -197,7 +197,6 @@ early_param("mem", early_mem); > static void __init setup_bootmem(void) > { > phys_addr_t vmlinux_end = __pa_symbol(&_end); > - phys_addr_t max_mapped_addr; > phys_addr_t phys_ram_end, vmlinux_start; > > if (IS_ENABLED(CONFIG_XIP_KERNEL)) > @@ -235,23 +234,9 @@ static void __init setup_bootmem(void) > if (IS_ENABLED(CONFIG_64BIT)) > kernel_map.va_pa_offset = PAGE_OFFSET - phys_ram_base; > > - /* > - * memblock allocator is not aware of the fact that last 4K bytes of > - * the addressable memory can not be mapped because of IS_ERR_VALUE > - * macro. Make sure that last 4k bytes are not usable by memblock > - * if end of dram is equal to maximum addressable memory. For 64-bit > - * kernel, this problem can't happen here as the end of the virtual > - * address space is occupied by the kernel mapping then this check must > - * be done as soon as the kernel mapping base address is determined. > - */ > - if (!IS_ENABLED(CONFIG_64BIT)) { > - max_mapped_addr = __pa(~(ulong)0); > - if (max_mapped_addr == (phys_ram_end - 1)) > - memblock_set_current_limit(max_mapped_addr - 4096); > - } > - > min_low_pfn = PFN_UP(phys_ram_base); > - max_low_pfn = max_pfn = PFN_DOWN(phys_ram_end); > + max_pfn = PFN_DOWN(phys_ram_end); > + max_low_pfn = min(max_pfn, PFN_DOWN(__pa(-PAGE_SIZE))); > high_memory = (void *)(__va(PFN_PHYS(max_low_pfn))); > > dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn)); Cheers, Andreas --Apple-Mail=_B97920C0-75B2-43B7-A029-2F2368082F1C Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIzBAEBCAAdFiEEDb73u6ZejP5ZMprvcqXauRfMH+AFAmYgSN0ACgkQcqXauRfM H+DTLw/9EwRBw0cRdgYXbwAYsBH4sVkfgtbtkgDwHRrlhS6n2fVLjymfTmEtn++p 28ksq83sFuQ/G5E6hPw5WOrOygWfww4hjLLM3kGvHf0iiMc7hR4ElbGEMbY8Iyu7 dA8A0aStRJHcJpYi0aMfUF2SCnCIAp1Q11JFgfw3g2sqNSWMUTw22R57BD6W8GJB 3zD+y/EhOWzT28zBq8sB55ynr6TVQXf/G/M7Kdr6QQ98oXEDVYLtdT0B0p4JaHXM TxQkijrAIJHHZ4oWd2B749JUwoq4zqtCUp9jaJkwfvuL2889TOdxNV4Ae0LHv51t k+N5NsQ8WILPQ+sIJezIHxswFkHLiczoVw6W9J/JQOq3PmiF3JeADAsLOgPOA7VH 8bicPF2GT+yi7amnzN5pdl7oB0rk/qQMlotJjzfCZpx/7hKOjeAA3m4PGLJDNnWV XaW47LVUJxk+LKjhTRIWXReNWVfpEMi/YnVyLSVg5CNl7FQPYq6ybhnVbwlOmcUr WZCqFJGuomrHtqOUSC/+oW2rREHDhw6s+noEC/g0X8sn5cfMMZognwxvqzgLd7AF taLTLPGuzc9PcbBlNRfapmCFUczLvbWY1+SjVh3Im8Yq2yaS95J/1kzSkSodexqh 9qHDAikxwiGJxK9HeqITFGaXg+Y9mn+frUuzKfFm1w2koGweqaI= =VbKS -----END PGP SIGNATURE----- --Apple-Mail=_B97920C0-75B2-43B7-A029-2F2368082F1C--