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b=kLNXU5knlHa3KmPye65lbh7Fo2+k3BFQRh76KUtsvTNCDRW1TugDSfOp598AyqSVf fQhV+bgMJdGNNbrlOy9NWbiClQdKu9qLLobOz0c2uZixhN9z5fYjCMZ1zfnv+lqPDm MPlNzKBTu6zceRDAFlc8KX1eg85HeXSoEDDk4nPr43jzIIuQgVn3qMf8+k6yqtCvBF rcks7qAJS9l4HXfUNu8okAJsU6UxRxP1B4uJQSD9P9WBtiD4zYKCHWq3IQylxKclrZ liXeuT5DYGZh3izx0OqIfZtiaannaqVNwIWiFlN38Bf2GD4k/Ic4uNgiR7fslAkBDy 2MxKm25Wvg8ZQ== Message-ID: Date: Mon, 29 Jun 2026 14:30:03 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 03/12] mm/rmap: refactor some code around lazyfree folio unmapping To: Dev Jain , akpm@linux-foundation.org, ljs@kernel.org, chrisl@kernel.org, kasong@tencent.com, hughd@google.com, liam@infradead.org Cc: riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, shikemeng@huaweicloud.com, nphamcs@gmail.com, bhe@redhat.com, youngjun.park@lge.com, baolin.wang@linux.alibaba.com, pfalcato@suse.de, ryan.roberts@arm.com, anshuman.khandual@arm.com References: <20260526063635.61721-1-dev.jain@arm.com> <20260526063635.61721-4-dev.jain@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: E9BDB40005 X-Stat-Signature: 3uxpf9rh1opsyqqwwpnzor9wdxo59zpq X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1782736212-807032 X-HE-Meta: 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 j85fqAk8 Ix5JCPpC3JPnRfTBKGHW6fJlM4wVNeQyW0thq2wPgGKRxIJjASl2bpRzkybvH0Y+871goyrtxP88gdco7fSZCWVFUJZtpXtQQv4M5ymQDy78x3LsqvE57m8umo6J/eoe43KVJ6dPwVm9F1om3tx0QYahwyO4mYMISKL6cRIH4QjM60RyA4OH/tztaTx9eyRh4WZ2SGFjyfuPxSjSCDNMvR/eT9McUzp9PR+Z0VqTVKSyGHjYgMQJ9xC6B/1ByIvM3hdhml4Dg6tra9WhB9LWnYwSeTqZdXxxaju1hFaOsLjiHRWso9wcBWX0NIQ69puXCioQd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 6/23/26 10:42, Dev Jain wrote: > > > On 09/06/26 7:50 pm, David Hildenbrand (Arm) wrote: >> On 5/26/26 08:36, Dev Jain wrote: >>> For lazyfree folio unmapping, after clearing the ptes we must abort the >>> operation if the folio got dirtied or it has unexpected references. >>> >>> Refactor this logic into a function which will return whether we need >>> to abort or not. >>> >>> If we abort, we restore the ptes and bail out of try_to_unmap_one. >>> Otherwise adjust the rss stats of the mm and jump to a label. >>> >>> Also rename that label from "discard" to "finish_unmap"; the former >>> is appropriate in the lazyfree context, but the code following the label >>> is executed for other successful unmap code paths too, so 'discard' does >>> not sound correct for them. >>> >>> Signed-off-by: Dev Jain >>> --- >>> mm/rmap.c | 88 +++++++++++++++++++++++++++++++------------------------ >>> 1 file changed, 50 insertions(+), 38 deletions(-) >>> >>> diff --git a/mm/rmap.c b/mm/rmap.c >>> index 06ab1158d4cd1..12bbee57f20da 100644 >>> --- a/mm/rmap.c >>> +++ b/mm/rmap.c >>> @@ -2093,6 +2093,52 @@ static bool try_to_unmap_hugetlb_one(struct folio *folio, >>> return ret; >>> } >>> >>> +static inline bool ttu_lazyfree_folio(struct vm_area_struct *vma, >>> + struct folio *folio) >> >> Nitty, but I wonder whether we want to return an int with 0 vs. -EBUSY instead. >> >> Reading "!ttu_lazyfree_folio" naturally makes me assume that this would be a >> success path (which it is not). > > You have a point but if you don't have a strong opinion I'll prefer to keep as is. > -EBUSY won't be consumed by the callers anyways : ) Yeah, works for me, the "try_to" part implies what a bool return code means. -- Cheers, David