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b=xoKMZzuj0I8JJZvIEyWy9EMohJxlbDU7BOafGQgQ+aeQ7NRZ8kZIETDvWSnIPCAbI nDkhHAKYR/ofR80su0ojMxOmY4XFt6zdYD1ASYs0OTNRCZPzB+61Ur34t5pMWf0yKY WY4PND6r+tbRW7v8HzA7RmR+PayCfiT1xrpI3t2g= Date: Tue, 7 Jul 2026 13:18:10 -0700 From: Andrew Morton To: Barry Song Cc: "David Hildenbrand (Arm)" , linux-mm@kvack.org, baoquan.he@linux.dev, chrisl@kernel.org, jp.kobryn@linux.dev, kasong@tencent.com, liam@infradead.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, nphamcs@gmail.com, rppt@kernel.org, shakeel.butt@linux.dev, shikemeng@huaweicloud.com, surenb@google.com, usama.arif@linux.dev, vbabka@kernel.org, youngjun.park@lge.com Subject: Re: [PATCH v3 2/4] mm: drop stale folio_ref_count()==1 check in do_swap_page reuse logic Message-Id: <20260707131810.96a4c1c56e00264b311133d8@linux-foundation.org> In-Reply-To: References: <20260701235955.36126-1-baohua@kernel.org> <20260701235955.36126-3-baohua@kernel.org> <3a185a5d-2f2c-4e9d-9cd9-8bdb236dfc5c@kernel.org> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8BB4B1A0002 X-Rspam-User: X-Stat-Signature: rbjpwr4itje77abueb6zma7u4i4sh6wj X-Rspamd-Server: rspam03 X-HE-Tag: 1783455492-217232 X-HE-Meta: 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 v0GMsl9I ar1N7tFx/D4lcmDtnkvPAXzuFwhryax8zCa9TcrOZbMn70qm2oZs4rz3ApDctGUxxZaKBQmrWWIkaBjBtYtbnpaZR0r6ecfGTGPNbya9UShWm/2xbP61Tf36tOGvzZyqFScFF6mhFvAeoPsWgsG35PFP9aylGyr1Cnbtfy4HISI2u+IUbm5hRCw4njyMDi6O34QpQHh4f6MpEo8LOMznf7z2v/E0F8tTEZAU+smeHKDti1zesmEd3+LSgwil2VttIISUV52zPBhmpNAyOY2DT9gbf/IgxGNFjuV0Pj35c1fMc2DfxYU31aekOJoVdxnEOH2uw Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 7 Jul 2026 19:08:13 +0800 Barry Song wrote: > > Sashiko points out two minor things (one flagged as medium, lol, sure sure). > > > > Here, you can clarify that folio_ref_count()==1 is true for freshly allocated > > pages (due to the KSM check) in which case exclusive=true already. > > Hi Andrew, > > I saw that you've queued this in mm-new. Thanks very much for that! > > Would you mind adding the following sentences to the end of the changelog? > > The ksm_might_need_to_copy() check may allocate a fresh folio with > folio_ref_count() == 1. Along that path, exclusive has already been > set to true, so the folio can still be reused correctly. Done, thanks.