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b=EJ+Bh5mDoFiVGST/VZ9LwjLJKNxgl8Don7jXz5gvsv1Gl9TQxigrS7FDok0K37418 N+I720wtH35BOkVZermgSzgA0IcVOAtDvD6kv1LggkTgO8BHAcM0QPq73lvJ2cCis8 DIONaBMWnco8GwTjT1SI9czmvq7ZzK3Ph9Q6ieNg= Date: Fri, 8 May 2026 12:24:22 -0700 From: Andrew Morton To: Frederick Mayle Cc: Matthew Wilcox , android-mm@google.com, kernel-team@android.com, Jan Kara , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/1] mm/readahead: simplify page_cache_ra_unbounded loop counter reset Message-Id: <20260508122422.00ec86bcaf2fd3685332830e@linux-foundation.org> In-Reply-To: References: <20260501011908.3630802-1-fmayle@google.com> <20260501061146.6e61392d125cf1847d7cc181@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=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: ram985jpihwm1ckpox8psp8wb8jgecsw X-Rspamd-Queue-Id: 6A7C6A0009 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1778268264-710174 X-HE-Meta: U2FsdGVkX1/TV6GE2jtwTIyIIE9kbiyepte/hkeTFk8CY8OJW0FFhEC7nWAPXr/Q9b5Sps0naNMiAR9MVUDVUALrpkcxLs7q46vbAhfOD6RtoL4BVqBnBZaeE7HELQGSajHeHrrG1zjrpRwSgdGSkWb748y5eBp0xoJ995JKj10Gmhqm4C0xu+XJ2p5koSpZ6yUSls2bSQeOTDuZF2M2tWkEP6U73232ByU18kfES3gAZyrBI6ziBaZbzWmqTaNNMnFfgJXtUE+52DrFzSD/UR5X4DzHelnge0kNLgXo4b1CgtNyM56EB/GmOwH3TdOwUHpuNhXFcEGV/bxTpRPwzY96alb1PI+6d/dOuKoYeCJDDPQZbT/p+W7mJwY6ybwGpadIwd8r2t5PYlj55on59BemtyzaZi50E2nTNt71dF4FonOzY0n6lMH3Ui8MHXhzWbSUxVkr0fycf296gFr1OPMMgpMsBC2z4DRtRD+I5mpGJYs0oGblikzlJkwnWIQVOhEWnBsrQbk+5g40vwcIEyQ8Q4fFD7eAJ7Mf8Uh/rnrMjIHIyM/95Drf3RGcWbXJ/POnSYaMGLhGfEQ4Ndk1AqJrIthz6wpUZGslzTDnfmuuRtFkh2Brvvq3KPU+AYRjh7sLTZZqQnt2Wk9o6G2gCuaVk9zatUXA2mH5lU/iTGN5b2ptKHbaLXaxPHkSRngtghgfvsIUMfGV6Wt1L+DAFYrTwQXMUdIsz+KpVnbF0c3U7IZXXiCVa3UPjT7c6Z5pMztYvAM+PTt633fzpSsMtLPiE/3mrJ85e2tYtxEhuLNZHUUfcAOJXPaAqkksQbqmTfCzEjuItKR5ahNLgfSmrlF889T62mYAtdnvAVd/NYNspyHZqdY1fjSR3ro+hKpXpwAcS6kGAoLEf4KoMH292UpwtSgo6N6UmQo7yupZw7VJH3RAK0TS0hLpAQ/uHRZYA2BRtJeH5RXbCHWgVSH NiLRujma ADqhnZoExkqcdoldeZcpmDVRCIJdd6yrek6RPeNYO8c+Sqxd+BRAvxHI9ucUKicqEhQh71JmzwNF7xOnXrLpnb0SmOT5fZBL2QS+qJ0qk9KwgWhsNqKublUls/aMUSfkisMlACJW2tAQ4WvG+OuBQ+Ex9Cj3CS97iwjT2bVTn5gLir3kUVnQdFpbIDTuk9brWInN5PZZfojJbBz2ioMPcNPxzDMGBrULBP3FqGcpTOMIAufsrsTwMHWdpZGrHpSYdlUi6Nq4NZpJn3expQzY/o8zJYMmiDIVmOqpii7KMCyHYcUKYiPdiXFdvujAO/dy6Dq5oo3kwdHRZz4eMZt2ViWhqxzx5oZH34tbSekQBV1RZZSPdy3p0ykDfD8HKk7mT1MqRB+1KD9HoYn2q8q3oOEMChQbdvLSdmSL8tS4xTU6x3Sk= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 7 May 2026 19:01:27 -0700 Frederick Mayle wrote: > On Fri, May 1, 2026 at 6:11 AM Andrew Morton wrote: > > > > On Thu, 30 Apr 2026 18:19:07 -0700 Frederick Mayle wrote: > > > > > Minor cleanup, no behavior change intended. > > > > > > `read_pages` ensures that `ractl->_nr_pages` is zero before it returns, > > > > So it seems, but depending upon this might be a bit fragile? > > > > It would be better to make this a more explicit/formal part of the > > read_pages() contract. kerneldocifying read_pages() would be a > > suitable way. > > I agree. I've sent the following patch to document the invariant > https://lore.kernel.org/r/20260508015402.735441-1-fmayle@google.com/ Thanks. I suggest you turn both into a single patch and resend when people have returned and recovered from the conference ;)