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Fri, 6 Mar 2026 15:20:26 -0500 (EST) Date: Fri, 6 Mar 2026 20:20:21 +0000 From: Kiryl Shutsemau To: Matthew Wilcox Cc: Chris J Arges , akpm@linux-foundation.org, william.kucharski@oracle.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@cloudflare.com Subject: Re: [PATCH RFC 1/1] mm/filemap: handle large folio split race in page cache lookups Message-ID: References: <20260305183438.1062312-1-carges@cloudflare.com> <20260305183438.1062312-2-carges@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: CCF5710000D X-Stat-Signature: oowbsztfy3xnuuuumiowa51xrf3rbnhh X-Rspam-User: X-HE-Tag: 1772828428-685029 X-HE-Meta: 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 K6C2ZC9Z 4lkFdzZr0lTHbNzRmBG/RnrY/p7OXrG8B8bQwqZRBKTnwNpuXW2iHvJHvlRJkTc/BStxVUFjbGZkkqsARH8er1xs9zgODeRqds+i3f0Skoe/+K39W+BV0xreJmOYelkB/E11Vy7/QLqbbst0hqBy5dDgo2QehzB7kC/FR+q2zAGLxy5ikyN3JIKF7pK3iky5lrSvqptmCeAb6HZ8Yg99JygimikHF5XH948utBVdB2hOVpJiz1e3FWoqc0NQCyBMVxCgVfKFRML6QThn+U7t8hnwkuJkDXfEnK4xxivRV0TZ4Y3wWsVKwhu3INcv3cGEumvHTHTTwmM43BrxUFlhnk42BhA41uJ2qLCJ+g1n7ibzpOGNbD84gNB26BRLkniZuuRjOcCXSFnKzZ0hpbImUYJYKAgg1jfc7M1uk/gUXpBWLr8f/SH5NGjszCg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Mar 06, 2026 at 06:41:08PM +0000, Matthew Wilcox wrote: > On Fri, Mar 06, 2026 at 06:36:30PM +0000, Kiryl Shutsemau wrote: > > The proposed change doesn't fix anything, but hides the problem. > > It would be better to downgrade the VM_BUG_ON_FOLIO() to a warning + > > retry. > > The trouble is that a retry only happens to work in ... whatever scenario > this is. If there's a persistent corruption of the radix tree, a retry > might be an infinite loop which isn't terribly helpful. Whether the problem is transient can be useful. -- Kiryl Shutsemau / Kirill A. Shutemov