From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C953DC433DB for ; Thu, 28 Jan 2021 03:13:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2050964DD3 for ; Thu, 28 Jan 2021 03:13:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2050964DD3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5B5DF6B0005; Wed, 27 Jan 2021 22:13:41 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 566646B0006; Wed, 27 Jan 2021 22:13:41 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 47DBD6B006C; Wed, 27 Jan 2021 22:13:41 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0039.hostedemail.com [216.40.44.39]) by kanga.kvack.org (Postfix) with ESMTP id 331F16B0005 for ; Wed, 27 Jan 2021 22:13:41 -0500 (EST) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id EED988249980 for ; Thu, 28 Jan 2021 03:13:40 +0000 (UTC) X-FDA: 77753713800.20.comb96_0b03c7f2759c Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id CCD80180C07A3 for ; Thu, 28 Jan 2021 03:13:40 +0000 (UTC) X-HE-Tag: comb96_0b03c7f2759c X-Filterd-Recvd-Size: 5746 Received: from szxga05-in.huawei.com (szxga05-in.huawei.com [45.249.212.191]) by imf31.hostedemail.com (Postfix) with ESMTP for ; Thu, 28 Jan 2021 03:13:39 +0000 (UTC) Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DR59Y4L1szMR3L; Thu, 28 Jan 2021 11:12:01 +0800 (CST) Received: from [10.174.177.80] (10.174.177.80) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.498.0; Thu, 28 Jan 2021 11:13:20 +0800 Subject: Re: [PATCH v11 01/13] mm/vmalloc: fix HUGE_VMAP regression by enabling huge pages in vmalloc_to_page To: Nicholas Piggin , , Andrew Morton CC: , , , Jonathan Cameron , Christoph Hellwig , Christophe Leroy , Rick Edgecombe , Christoph Hellwig References: <20210126044510.2491820-1-npiggin@gmail.com> <20210126044510.2491820-2-npiggin@gmail.com> From: Ding Tianhong Message-ID: <2dcbe2c9-c968-4895-fc43-c40dfe9f06d3@huawei.com> Date: Thu, 28 Jan 2021 11:13:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.3.2 MIME-Version: 1.0 In-Reply-To: <20210126044510.2491820-2-npiggin@gmail.com> Content-Type: text/plain; charset="utf-8" Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.80] X-CFilter-Loop: Reflected X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2021/1/26 12:44, Nicholas Piggin wrote: > vmalloc_to_page returns NULL for addresses mapped by larger pages[*]. > Whether or not a vmap is huge depends on the architecture details, > alignments, boot options, etc., which the caller can not be expected > to know. Therefore HUGE_VMAP is a regression for vmalloc_to_page. > > This change teaches vmalloc_to_page about larger pages, and returns > the struct page that corresponds to the offset within the large page. > This makes the API agnostic to mapping implementation details. > > [*] As explained by commit 029c54b095995 ("mm/vmalloc.c: huge-vmap: > fail gracefully on unexpected huge vmap mappings") > > Reviewed-by: Christoph Hellwig > Signed-off-by: Nicholas Piggin > --- > mm/vmalloc.c | 41 ++++++++++++++++++++++++++--------------- > 1 file changed, 26 insertions(+), 15 deletions(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index e6f352bf0498..62372f9e0167 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -34,7 +34,7 @@ > #include > #include > #include > - > +#include > #include > #include > #include > @@ -343,7 +343,9 @@ int is_vmalloc_or_module_addr(const void *x) > } > > /* > - * Walk a vmap address to the struct page it maps. > + * Walk a vmap address to the struct page it maps. Huge vmap mappings will > + * return the tail page that corresponds to the base page address, which > + * matches small vmap mappings. > */ > struct page *vmalloc_to_page(const void *vmalloc_addr) > { > @@ -363,25 +365,33 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) > > if (pgd_none(*pgd)) > return NULL; > + if (WARN_ON_ONCE(pgd_leaf(*pgd))) > + return NULL; /* XXX: no allowance for huge pgd */ > + if (WARN_ON_ONCE(pgd_bad(*pgd))) > + return NULL; > + > p4d = p4d_offset(pgd, addr); > if (p4d_none(*p4d)) > return NULL; > - pud = pud_offset(p4d, addr); > + if (p4d_leaf(*p4d)) > + return p4d_page(*p4d) + ((addr & ~P4D_MASK) >> PAGE_SHIFT); > + if (WARN_ON_ONCE(p4d_bad(*p4d))) > + return NULL; > > - /* > - * Don't dereference bad PUD or PMD (below) entries. This will also > - * identify huge mappings, which we may encounter on architectures > - * that define CONFIG_HAVE_ARCH_HUGE_VMAP=y. Such regions will be > - * identified as vmalloc addresses by is_vmalloc_addr(), but are > - * not [unambiguously] associated with a struct page, so there is > - * no correct value to return for them. > - */ > - WARN_ON_ONCE(pud_bad(*pud)); > - if (pud_none(*pud) || pud_bad(*pud)) > + pud = pud_offset(p4d, addr); > + if (pud_none(*pud)) > + return NULL; > + if (pud_leaf(*pud)) > + return pud_page(*pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT); Hi Nicho: /builds/1mzfdQzleCy69KZFb5qHNSEgabZ/mm/vmalloc.c: In function 'vmalloc_to_page': /builds/1mzfdQzleCy69KZFb5qHNSEgabZ/include/asm-generic/pgtable-nop4d-hack.h:48:27: error: implicit declaration of function 'pud_page'; did you mean 'put_page'? [-Werror=implicit-function-declaration] 48 | #define pgd_page(pgd) (pud_page((pud_t){ pgd })) | ^~~~~~~~ the pug_page is not defined for aarch32 when enabling 2-level page config, it break the system building. > + if (WARN_ON_ONCE(pud_bad(*pud))) > return NULL; > + > pmd = pmd_offset(pud, addr); > - WARN_ON_ONCE(pmd_bad(*pmd)); > - if (pmd_none(*pmd) || pmd_bad(*pmd)) > + if (pmd_none(*pmd)) > + return NULL; > + if (pmd_leaf(*pmd)) > + return pmd_page(*pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT); > + if (WARN_ON_ONCE(pmd_bad(*pmd))) > return NULL; > > ptep = pte_offset_map(pmd, addr); > @@ -389,6 +399,7 @@ struct page *vmalloc_to_page(const void *vmalloc_addr) > if (pte_present(pte)) > page = pte_page(pte); > pte_unmap(ptep); > + > return page; > } > EXPORT_SYMBOL(vmalloc_to_page); >