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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C6E6C4345F for ; Wed, 1 May 2024 08:05:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 00CAB6B0093; Wed, 1 May 2024 04:05:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id EFF126B0096; Wed, 1 May 2024 04:05:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DED546B0099; Wed, 1 May 2024 04:05:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id C828F6B0093 for ; Wed, 1 May 2024 04:05:23 -0400 (EDT) Received: from smtpin18.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 6753EC0AC3 for ; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 4EE7140005 X-Stat-Signature: 1itygdowychi93reaqqhsmhysj47nbs7 X-HE-Tag: 1714550721-800232 X-HE-Meta: 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 tHEHwCaT 49QKb8GmtqKpDbCiGdq4n4+aoBCI/0JpP4D0Wa5LPZcPretq735ij8EODtwBWTvjzR/OMu5+6kEUXqmPBGKAmcPLAaaXosWKlMC083OdxI2WcGQ0Z1k1ReiK/7IIny8dvi9+1XY68EPmJ0jPzZmjZ2VrSdIVJGiXPZw3sJ1ONJTzjwvhYRUeOrYlq4xAFf6GIIHSDAgSgDNKE0NsMZCfAZnEibBMepl0Wp2GObW5reCyMqHsRA/DoM+YWGDOy5Y/Phtlc 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: List-Subscribe: List-Unsubscribe: On 30/04/2024 18:57, Catalin Marinas wrote: > On Tue, 30 Apr 2024 14:31:38 +0100, Ryan Roberts wrote: >> __split_huge_pmd_locked() can be called for a present THP, devmap or >> (non-present) migration entry. It calls pmdp_invalidate() >> unconditionally on the pmdp and only determines if it is present or not >> based on the returned old pmd. >> >> But arm64's pmd_mkinvalid(), called by pmdp_invalidate(), >> unconditionally sets the PMD_PRESENT_INVALID flag, which causes future >> pmd_present() calls to return true - even for a swap pmd. Therefore any >> lockless pgtable walker could see the migration entry pmd in this state >> and start interpretting the fields (e.g. pmd_pfn()) as if it were >> present, leading to BadThings (TM). GUP-fast appears to be one such >> lockless pgtable walker. >> >> [...] > > Applied to arm64 (for-next/fixes), thanks! It should land in 6.9-rc7. I > removed the debug/test code, please send it as a separate patch for > 6.10. Thanks Catalin! I'm guessing this will turn up in today's linux-next, so if I send the tests today and Andrew puts them straight in mm-unstable (which will goto linux-next) there is no risk that the tests are there without the fix? Or do I need to hold off until the fix is in v6.9-rc7? > > [1/1] arm64/mm: pmd_mkinvalid() must handle swap pmds > https://git.kernel.org/arm64/c/e783331c7720 >