lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-ID: <6840f4f65a981_2491100b3@dwillia2-xfh.jf.intel.com.notmuch> Date: Wed, 4 Jun 2025 18:37:58 -0700 From: Dan Williams <dan.j.williams@...el.com> To: Alistair Popple <apopple@...dia.com>, <linux-mm@...ck.org> CC: Alistair Popple <apopple@...dia.com>, <gerald.schaefer@...ux.ibm.com>, <dan.j.williams@...el.com>, <jgg@...pe.ca>, <willy@...radead.org>, <david@...hat.com>, <linux-kernel@...r.kernel.org>, <nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>, <linux-ext4@...r.kernel.org>, <linux-xfs@...r.kernel.org>, <jhubbard@...dia.com>, <hch@....de>, <zhang.lyra@...il.com>, <debug@...osinc.com>, <bjorn@...nel.org>, <balbirs@...dia.com>, <lorenzo.stoakes@...cle.com>, <linux-arm-kernel@...ts.infradead.org>, <loongarch@...ts.linux.dev>, <linuxppc-dev@...ts.ozlabs.org>, <linux-riscv@...ts.infradead.org>, <linux-cxl@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>, <John@...ves.net> Subject: Re: [PATCH 02/12] mm: Convert pXd_devmap checks to vma_is_dax Alistair Popple wrote: > Currently dax is the only user of pmd and pud mapped ZONE_DEVICE > pages. Therefore page walkers that want to exclude DAX pages can check > pmd_devmap or pud_devmap. However soon dax will no longer set PFN_DEV, > meaning dax pages are mapped as normal pages. > > Ensure page walkers that currently use pXd_devmap to skip DAX pages > continue to do so by adding explicit checks of the VMA instead. tl;dr: Reviewed-by: Dan Williams <dan.j.williams@...el.com> So I went through all the p[mu]d_devmap() checks and indeed this is the set I also come up with that are implicitly checking for "dax" instead of checking for "is this a larger than base pte size mapping". While I am a little uncomfortable with the generality of calling the policy "dax" in these locations I think it is ok for now. I.e. the fundamental detail in these paths is "huge pte, but not typical page-allocator THP page" Also I would have felt better if some of the leftover places that are doing "dax" checks but not updated were noted in the changelog just for review purposes. Like: "Note paths like follow_huge_pud and follow_pmd_mask also have 'dax' checks, but those paths are for maintaining dev_pagemap refcounts which no longer (since v6.15) need to be managed for dax pages. A later patch cleans those up."
Powered by blists - more mailing lists