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b=RmoNemMUl1sw1JOPWhVSmESnBtwY1VrPO/I9sWWI9ZARdWfoHuKCcSDnVrOkHjazk z2i+CNKwtjiY+GMjqll+fCd7a2Iimzob44CQSFXocON4Qe2xHIP8L3AO0n7ZN+BP1x eIQnQNCUW88YNkR19rYBD6YtlIfmvSYo0Q+FOf1M= Date: Wed, 8 Oct 2025 18:07:44 -0700 From: Andrew Morton To: Lance Yang Cc: david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, ioworker0@gmail.com, richard.weiyang@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH mm-new v3 3/3] mm/khugepaged: merge PTE scanning logic into a new helper Message-Id: <20251008180744.008424134fbc29e9616899ad@linux-foundation.org> In-Reply-To: <20251008043748.45554-4-lance.yang@linux.dev> References: <20251008043748.45554-1-lance.yang@linux.dev> <20251008043748.45554-4-lance.yang@linux.dev> 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-Queue-Id: E3247120004 X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: 3773gb4t1e48bbequcp4pob59bmxsks3 X-HE-Tag: 1759972066-892464 X-HE-Meta: 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 R3TgfWwK T1ufXF7NnY/3PvL3KDlAEwJZWtxCXGINSHLjMbnj5Po6HiqeQxVks03DF/ALyZ7uhAJvJbyuBQEPbIP7djSDlr4Pyh/fnaaB5jwDsM1b3qpJKWTSdcmUT5mRnQ6GmpcPopx2EQiDwZsHcu0deNYwpXmnMMTOa9mTBFAPVtESiPXgCc/qWGiwjvMiPkt312/pksFz+/boZCgbzLsMEbry38HlcLHxawiiV3bqs1OQwganH6PSP5k/9LWkAqrf7dNr23SRSAupXaKBeBfeb8rEY0wjod0S55dLrIzRvxJEGvVWsXoe01FjXpM/ZDFABudjttkAdodbprYDTumFv6AKPT3Ca5L8RZnA+mZgLQf+pN9DQ0NI= 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 Wed, 8 Oct 2025 12:37:48 +0800 Lance Yang wrote: > + if (!cc->is_khugepaged || > + *unmapped <= khugepaged_max_ptes_swap) { > + /* > + * Always be strict with uffd-wp enabled swap > + * entries. Please see comment below for > + * pte_uffd_wp(). > + */ > + if (pte_swp_uffd_wp(pte)) { > + *scan_result = SCAN_PTE_UFFD_WP; > + return PTE_CHECK_FAIL; > + } > + return PTE_CHECK_CONTINUE; > + } else { > + *scan_result = SCAN_EXCEED_SWAP_PTE; > + count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); > + return PTE_CHECK_FAIL; > + } I'm inclined to agree with checkpatch here. WARNING: else is not generally useful after a break or return #81: FILE: mm/khugepaged.c:574: + return PTE_CHECK_CONTINUE; + } else { did you see this and disagree or did you forget to run checkpatch? --- a/mm/khugepaged.c~mm-khugepaged-merge-pte-scanning-logic-into-a-new-helper-checkpatch-fixes +++ a/mm/khugepaged.c @@ -571,11 +571,10 @@ static inline int thp_collapse_check_pte (!cc->is_khugepaged || *none_or_zero <= khugepaged_max_ptes_none)) { return PTE_CHECK_CONTINUE; - } else { - *scan_result = SCAN_EXCEED_NONE_PTE; - count_vm_event(THP_SCAN_EXCEED_NONE_PTE); - return PTE_CHECK_FAIL; } + *scan_result = SCAN_EXCEED_NONE_PTE; + count_vm_event(THP_SCAN_EXCEED_NONE_PTE); + return PTE_CHECK_FAIL; } else if (!pte_present(pte)) { if (!unmapped) { *scan_result = SCAN_PTE_NON_PRESENT; @@ -600,11 +599,10 @@ static inline int thp_collapse_check_pte return PTE_CHECK_FAIL; } return PTE_CHECK_CONTINUE; - } else { - *scan_result = SCAN_EXCEED_SWAP_PTE; - count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); - return PTE_CHECK_FAIL; } + *scan_result = SCAN_EXCEED_SWAP_PTE; + count_vm_event(THP_SCAN_EXCEED_SWAP_PTE); + return PTE_CHECK_FAIL; } else if (pte_uffd_wp(pte)) { /* * Don't collapse the page if any of the small PTEs are _