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Received: from DESKTOP-5N7EMDA(mailfrom:ying.huang@linux.alibaba.com fp:SMTPD_---0X1J0Agi_1776672067 cluster:ay36) by smtp.aliyun-inc.com; Mon, 20 Apr 2026 16:01:08 +0800 From: "Huang, Ying" To: Sunny Patel Cc: Andrew Morton , David Hildenbrand , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Alistair Popple , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm/migrate_device: Cleanup up PMD Checks and warnings In-Reply-To: <20260419174747.10701-1-nueralspacetech@gmail.com> (Sunny Patel's message of "Sun, 19 Apr 2026 23:17:43 +0530") References: <20260419174747.10701-1-nueralspacetech@gmail.com> Date: Mon, 20 Apr 2026 16:01:05 +0800 Message-ID: <87tst6hxha.fsf@DESKTOP-5N7EMDA> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: imxzmspfdbmrr133kg8nmbh5heek7yns X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6945B14000D X-HE-Tag: 1776672072-139946 X-HE-Meta: U2FsdGVkX1+bsN6u7sWRY2VPK5W0pu0jZcPfG57jxWw9z4zmOZHKoZQN9m+px32z7aSUQM0OsN5cybwONuhI0ftfwwPnlIZdcNm6+aDjp+pa3JtT+eg51uPzUzi/1DwTwf+/C8gSss5zKKvNjO4m+z5QDySJMAk/3HgTf3iLaoYgl/nm032l4i8O9gGeyUPmrcyxVmvVXfwztj86Gde8eFBRJ6jBJgUP+Yt0zzjn1CAPy0j43dd71TYl+QMwASE3C8yafzwbAA7NKTs8/U8wu0AfHdi1k0DxK7tOXy6IBrMSGbiCN97EIoalvgYPmFAifN5WIDiKxi30yjvFV8IwayoYC15vSuXXENmfD2MIdZebW7rO24FDComjZoa+NPwL8xxzzGXW95vbnIoD1owoN74CDLPiwiMF2rJtN35uTkTDWsqwQ1v8vVVpLq3SuFjGGf67nsozXlXR3x8LhkTR7v37BsIbBWUJg2WzJyXua5hntogmwqIbAE5PQ3BXtahThPf50/kDpM9a++Qnf8b2knBCH0su/7++NubfufTYxkZnybmsr5dzmryzZGBGKl7jPMbsmLzqO1Juf264idk0tFr82I15SUesekuTbFyyu9hSX1z/JuRnUjHsliPqgkN/SdLaurJTIaoc8qjgeiUhWbQ1dGNY89WKFZPTver7/raVEn/x0roy84J0vEgMvmvvMtlbuVu0VyBdu9GHKGOzO+3uc/CsQpb6sb51PT5vBdFL/eW8vPCOzclt7Mc17g4u8J71xwHOyHn0AfUEpUCvjh+/R19c+qDSLYLrYVsfSkAT0Kl5Xy53MrKG2UbibBOwR83F0ZaFodMFEuPFlNudm8zBKkbxNyLNQqNivw+fUBWlkt/Y+MyRD36zQuicXGqyCox3MEt61wQWYy0dLYaBOB2cwRFOy88ui6LbiU0A+q54GhpKfgNQKi4U8eMUlsc8qX1gB+61kBPAj2FcoIr MLQ3r7fX mB3Bkr0ICcY5n1rWxuBQwYr0Xr/tithViu3ZSYWS5Mn3VTNDI2Hx7kRK2mzUME6onA9bZnEGFIEMIpl0g7QZGluMwvJaJ7OfeJBdv4aAjs4GTskVlz3GaeobYXSAogG9CErwao3gQ0pUUTW0dlVu0x5dSa4GOiZRl/ccCJmLuhd70HiuRpnfGag/yk/15vsA6ot8UKsMyAGFeYZjvjpEd1C0kbDQ41cG9zjX0eis/r7LExJnJU3Ympd1OWypbymPFKqAGE7TNmpLJTeYCITGpHkaR7ORc8X90cDBbHmfSthRsBm/huZ0fm/kRT5+X4LDECnpZwz0GUo/gaY7a2FhbVg0KLkiAwmR12SQ4Aj32BDQgHigYx6J+jCrmg2VHIteFLR7abXIPHjwyG3S7OkG9SLyasA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Sunny Patel writes: > Remove the odd VM_WARN_ON_FOLIO(!folio, folio) usage and replace it > with a simpler VM_WARN_ON_ONCE(!folio) check. > > Drop the redundant VM_WARN_ON_ONCE(!pmd_none(*pmdp) && > !is_huge_zero_pmd(*pmdp)). > > Refactor the PMD checks, making the control flow > clearer and avoiding duplicate condition checks. > > Signed-off-by: Sunny Patel > --- > > Changes in v2: > - Removed additional check for pmd_present() as is_huge_zero_pmd() > already checks for pmd_present(). > > Missed it in first version of this patch. > > mm/migrate_device.c | 9 +++------ > 1 file changed, 3 insertions(+), 6 deletions(-) > > diff --git a/mm/migrate_device.c b/mm/migrate_device.c > index 8079676c8f1f..2c7e89a6d1b1 100644 > --- a/mm/migrate_device.c > +++ b/mm/migrate_device.c > @@ -807,8 +807,7 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, > bool flush = false; > unsigned long i; > > - VM_WARN_ON_FOLIO(!folio, folio); > - VM_WARN_ON_ONCE(!pmd_none(*pmdp) && !is_huge_zero_pmd(*pmdp)); > + VM_WARN_ON_ONCE(!folio); > > if (!thp_vma_suitable_order(vma, addr, HPAGE_PMD_ORDER)) > return -EINVAL; > @@ -865,11 +864,9 @@ static int migrate_vma_insert_huge_pmd_page(struct migrate_vma *migrate, > if (userfaultfd_missing(vma)) > goto unlock_abort; > > - if (!pmd_none(*pmdp)) { > - if (!is_huge_zero_pmd(*pmdp)) > - goto unlock_abort; > + if (is_huge_zero_pmd(*pmdp)) > flush = true; > - } else if (!pmd_none(*pmdp)) > + else if (!pmd_none(*pmdp)) > goto unlock_abort; > > add_mm_counter(vma->vm_mm, MM_ANONPAGES, HPAGE_PMD_NR); LGTM, feel free to add my Reviewed-by: Huang Ying in the future versions. --- Best Regards, Huang, Ying