From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 419C136AE1 for ; Thu, 29 Feb 2024 06:18:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709187523; cv=none; b=HURIHccj01g3v1NJDvWtvbXDzvbwxFMK2Zxnt60SxI/nAOK4tB02KuZXP/TciKZzDnisg0mumWssphG3vZFkrst4Eg1tN1pepa0MP03gsiwTzWMzCZDJjAZvxyLKGiynaL0Qyuh+ZugtaK2HLCMDvHVQR9g5jlDjg519vxrrEMU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709187523; c=relaxed/simple; bh=+qbymGl2a1QToFGQyExG9ZunXLOUJI8LBQgEqoKp1jw=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=u7qRztuE4fPsAS4rrX5lFOEwt1P6KLpQ+zQocT2enxR2JxjLcjQVLgylMAwkJ/P/v4ffWpmabuRFdvzQBlaOrhdIDzubCCfOMLCyK5EyrT+sqcocuNTUhrq0DtDFhVLqmGG69Qyn2h+QN306Bnn+lHFmU18CbIbrRmL2+WE3RPE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au; spf=pass smtp.mailfrom=ellerman.id.au; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b=C9OlH+RA; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ellerman.id.au Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="C9OlH+RA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1709187517; bh=3rPcoNkAXcpWZ8q00u4PWHD9ZMXVCcKe51zCGK/zmmM=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=C9OlH+RAEQUYEF7CvXeN3khlG4AxZoOiNYU73WWD1H8X2VDBDwqNgHd0etKpmeWrN SHdXc29fjfrEbAQdqE6vY0Cn1myrZKg8MCNPvP5MQjeJ5yWkKVPRSIymIuM4z5fLEF 2BDqpFy21V/Ph3RHC+BXNb2i2D6pEwU0yM+FNBC4ET6af7hAS7D9njOCl//qbQzrEw fNDlDc3jr0BQdJQFj1Z9GRrPZgefCXIk6xk75bgo1lWtkbCPTjAjpa03+Q+18mxCy0 SKuauHA6gl+sszlKKoGImJTBepG+q7ueFWHzJyOJfsp9y2bMw7Wf90712sQKWIE1Rg trl7/rdZQ1c/g== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4Tlgyh4k9sz4wc5; Thu, 29 Feb 2024 17:18:36 +1100 (AEDT) From: Michael Ellerman To: "Aneesh Kumar K.V" , Kunwu Chan , npiggin@gmail.com, christophe.leroy@csgroup.eu, naveen.n.rao@linux.ibm.com Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] powerpc/mm: Code cleanup for __hash_page_thp In-Reply-To: <87bk80kjup.fsf@kernel.org> References: <20240125092624.537564-1-chentao@kylinos.cn> <87h6hva4b0.fsf@mail.lhotse> <87jzmq5tjr.fsf@mail.lhotse> <87bk80kjup.fsf@kernel.org> Date: Thu, 29 Feb 2024 17:18:32 +1100 Message-ID: <87wmqng5dz.fsf@mail.lhotse> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Aneesh Kumar K.V writes: > Michael Ellerman writes: >> Kunwu Chan writes: >>> On 2024/2/26 18:49, Michael Ellerman wrote: >>>> Kunwu Chan writes: >>>>> This part was commented from commit 6d492ecc6489 >>>>> ("powerpc/THP: Add code to handle HPTE faults for hugepages") >>>>> in about 11 years before. >>>>> >>>>> If there are no plans to enable this part code in the future, >>>>> we can remove this dead code. >>>> >>>> I agree the code can go. But I'd like it to be replaced with a comment >>>> explaining what the dead code was trying to say. >> >>> Thanks, i'll update a new patch with the following comment: >>> /* >>> * No CPU has hugepages but lacks no execute, so we >>> * don't need to worry about cpu no CPU_FTR_COHERENT_ICACHE feature case >>> */ >> >> Maybe wait until we can get some input from Aneesh. I'm not sure the >> code/comment are really up to date. > > How about? > > modified arch/powerpc/mm/book3s64/hash_hugepage.c > @@ -58,17 +58,13 @@ int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid, > return 0; > > rflags = htab_convert_pte_flags(new_pmd, flags); > + /* > + * THPs are only supported on platforms that can do mixed page size > + * segments (MPSS) and all such platforms have coherent icache. Hence we > + * don't need to do lazy icache flush (hash_page_do_lazy_icache()) on > + * noexecute fault. > + */ Yeah thanks that looks good. It could say "see eg. __hash_page_4K()", but that's probably unnecessary as it mentions hash_page_do_lazy_icache(), and anyone interested is just going to grep for that anyway. cheers