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b=AbFmM/nqEku80UT+Aw7V4iA4reTs6onG88eMdzcmBom8o9iffpHF/sioYmaT8MFxS LtxEjSXM4LrFlC9dmF1WxtG5wWM5ScaShfstE/EfTPFnEroTAzaqvaVB/nvIHa3+AH 4zDgcBgJtT+PVaa/K+cc2GU+45UEeNZmfpm9XFddPWcMaaxD0yOcaxDjMtqh2b4rkZ RJYozXPKbhWQCK5W3LEtL7Q4isI94VLRu+djE6ouv7LG3VcAcRDhr61UVV7ozu24bo i7U7SJrXOA+NSjKiHxDwQk6QodHCsJc1KAfo8LO/Kpw2Ya3dK0XfB/CrLALFZbMXy6 R3tK7qaGprDsg== Message-ID: <3be96a1c-7cfb-4cd0-a4fb-16209494d041@kernel.org> Date: Mon, 26 Oct 2026 12:26:39 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] khugepaged: fix readahead lock inversion in collapse_file() To: Baolin Wang , Lance Yang , Pedro Falcato Cc: akpm@linux-foundation.org, ziy@nvidia.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, usama.arif@linux.dev, kas@kernel.org, jack@suse.cz, djwong@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, hch@lst.de, syzbot+16bf7cd0ebeb1de93aa5@syzkaller.appspotmail.com, ngocthang2710.1999@gmail.com, willy@infradead.org, rppt@kernel.org, ljs@kernel.org References: <20261016065920.4153-1-lance.yang@linux.dev> <27e5aadc-2d68-428f-a958-308e4a75c058@linux.alibaba.com> <6a005d89-df5b-4524-a4b9-c637cb15f1ee@linux.alibaba.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 7B5F0120002 X-Stat-Signature: j4f3z631q37nomtrnimum7ugtxjenype X-Spam-Status: No, score=-7.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793016746-254701 X-HE-Meta: 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 vTaCyJD4 lZZ/ESMX2u4MvclYa5Y2z/fT/Nh47clNHog0E5kbJQ1lOSFLcg7CzqXJwrizXtFe+rfYazqjBGgogk+qehHBsyZbIV6Kly65Ysc4PMeEdAueB0z4Wiiw40fgHBObvX72AcEnRhWZsqhiSSXqbwIWERCT/PG8J1K5hePo5p4JQILvPlnXLN/gQWWjBcw//GhtsIwWLenO3cIyxKkRgooBOf7MeCDH4YBaAkWFIg+p7ABOKlcKjj7Vs9iVyCtSMu7a498DA7dSE32el3QqUgzKIjCUa+q/+o8ubOpylD0TUJpYAxS5KMoHRAcVyGI54W8XVHOPRdGJpNat/UIpXc5g+YiMEISZerf6F+N6ZUCcsrY0XzNvt3eXdg3Mojs1F6hMsP46Ryu3cmMu5EpRep5M/SlyAPBLQoD+Nv1CgzdYEyI6PS011tWYEIg4SuTGGVlw0ybyd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/18/26 04:47, Baolin Wang wrote: > > > On 10/17/26 3:41 PM, Lance Yang wrote: >> >> >> On 2026/10/17 13:43, Baolin Wang wrote: >>> >>> >>> >>> OK. >>> >>> >>> Sounds good. >>> >>> >>> But why not add RA logic in collapse_pmd(), as we do for >>> SCAN_PAGE_DIRTY_OR_WRITEBACK? There's already retry logic there, and this >>> would also simplify the long collapse_file(). >> >> That would be cleaner, yeah. Some older stable trees don't have that >> outer retry loop, though ... I'd prefer to get the fix backported first, >> then move the RA/retry logic out in a follow-up, wdyt? > > IIRC, the approach to bug fixes is to fix bugs properly and cleanly for > upstream, without being constrained by backporting requirements. > > Anyway, I don't have a strong opinion on this. Let's also see what David prefers. Let's get this fixed in a acceptable way in a reasonable timeframe; it's been broken for too long. ... and follow up with bigger cleanups later. @Lance is this version good to review for that purpose or are you planning a resend? -- Cheers, David