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b=k55W2weXz5QLrUx7/EGmnM9f9o1yd7C9lmRdx4eUCBvC+3r1zZjn/y3JezTbd+QSF N9LcGAsObgVsQl8lbvzWuuY8/ozHgV88sYmGgMLVmlbir61lBizHUb095JnbZjQH22 o6/Zm0QMhqwCFQXzXM9Ru7MzXh4YHGiRgoGHxhyA= Date: Tue, 4 Nov 2025 14:24:45 -0800 From: Andrew Morton To: YoungJun Park Cc: linux-mm@kvack.org, Kemeng Shi , Kairui Song , Nhat Pham , Baoquan He , Barry Song , Chris Li , stable@vger.kernel.org Subject: Re: [PATCH v2 1/1] mm: swap: remove duplicate nr_swap_pages decrement in get_swap_page_of_type() Message-Id: <20251104142445.47e68d38b36c81aa304b55cc@linux-foundation.org> In-Reply-To: References: <20251102082456.79807-1-youngjun.park@lge.com> <20251103185608.84b2d685fe0ae4596307b878@linux-foundation.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-Server: rspam05 X-Rspamd-Queue-Id: 202E34000F X-Stat-Signature: k5nc7rxed5izpo1gew4x3f6gibfprwyt X-Rspam-User: X-HE-Tag: 1762295086-400667 X-HE-Meta: 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 /MLakxlp x9JFQ7gMbey1v3LHYOul4JZxIk8DxtSSwR8LseRifmMKBl4Zh/4eW9NHBWTDw13fpWCT8s/offsL/WSO9HbbBC4w+NnEVRHpRXx1Mk0gzD2MRA3dlZjDgnU1VoEam9g3Ie8TIHQtnMoI27d8Hybf3YozBVJl7BQikFv0raD31JptdhIYGHhPYh9+N2SCX5MDR3DnD9UKrM4lw2kkoICp8h+GH5N384GtB589a+pcPcytMYtSlC6rbgs8CsV9C3gyqyEVle2shxtrmcsKvlAGneOaUN3QZmV/vQycUF45+4TUOp8IJZjhce9nSWGUMWrenP/omtDuZGfEGD4u++AjynSNAKA== 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 Tue, 4 Nov 2025 23:46:40 +0900 YoungJun Park wrote: > > Can we please have a description of the userspace-visible runtime > > effects of the bug? > > > Fixes: 4f78252da887 ("mm: swap: move nr_swap_pages counter decrement from folio_alloc_swap() to swap_range_alloc()") > > > Cc: stable@vger.kernel.org # v6.17-rc1 > > > > Especially when proposing a backport. > > > > Thanks. > > Hi Andrew, > > Thank you for picking up the patch. Since it's already in mm-hotfixes-unstable, > I'm providing the elaboration here rather than sending v3. > > As a representative userspace-visible runtime example of the impact, > /proc/meminfo reports increasingly inaccurate SwapFree values. The > discrepancy grows with each swap allocation, and during hibernation when > large amounts of memory are written to swap, the reported value can deviate > significantly from actual available swap space, misleading users and > monitoring tools. Great, thanks, very helpful. I pasted that into the mm.git copy of this patch.