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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rsaH6-00000009WHm-2K1c; Fri, 05 Apr 2024 03:29:56 +0000 Date: Fri, 5 Apr 2024 04:29:56 +0100 From: Matthew Wilcox To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Janosch Frank , Claudio Imbrenda , Gerald Schaefer , Thomas Huth Subject: Re: [PATCH v1 2/5] s390/uv: convert gmap_make_secure() to work on folios Message-ID: References: <20240404163642.1125529-1-david@redhat.com> <20240404163642.1125529-3-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240404163642.1125529-3-david@redhat.com> X-Rspamd-Queue-Id: A3C3680008 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: jn4wnng6ytqw65kuwq8j1wgqmfk3q8hh X-HE-Tag: 1712287799-311076 X-HE-Meta: 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 BdUUvAwa XmgrUjpMgzMIU7+izyw3yfEZ1DyIfHqflhNQwWGk2Aw3iR9S3ibtnZrMr1n3y44VfPwYioyEGdNW5jvpGtl+OJCiBA32DJR5LfmHhNT3jf0LIRf8sHBA95DzNsKWkXfUFkPa5/YJnld3ZSdLwc8xB67ocyhSwgR/hZjuS4CwBRJ35ih5pigbt4/NtVQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000336, 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 Thu, Apr 04, 2024 at 06:36:39PM +0200, David Hildenbrand wrote: > + /* We might get PTE-mapped large folios; split them first. */ > + if (folio_test_large(folio)) { > + rc = -E2BIG; We agree to this point. I just turned this into -EINVAL. > > + if (rc == -E2BIG) { > + /* > + * Splitting might fail with -EBUSY due to unexpected folio > + * references, just like make_folio_secure(). So handle it > + * ahead of time without the PTL being held. > + */ > + folio_lock(folio); > + rc = split_folio(folio); > + folio_unlock(folio); > + folio_put(folio); > + } Ummm ... if split_folio() succeeds, aren't we going to return 0 from this function, which will be interpreted as make_folio_secure() having succeeded?