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Tue, 25 Aug 2026 10:27:47 +0000 (UTC) X-FDA: 85139415774.29.A284D22 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf06.hostedemail.com (Postfix) with ESMTP id 9A743180004 for ; Tue, 25 Aug 2026 10:27:45 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=ShPy4092; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787653665; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=AmTIRDghT5aZb5UGuzctLRIrFioVqTHUxr0Sp616qgk=; b=iDRd7V+2c/anXI7WOzy0Ko5AVnoUQfmuTFkmMy7r/kqEU1GGBRVgdGPCdo+Ao7yK3xqTK2 /HTCKMIp8f6cYdUDD0X72Oqj6k8tqPQt9Fbg15NKZGNgBDmO0uSbdHEGLpZa73NelyHonI 14VESdl7bCTsuhAku85NXARy+dM8W4k= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=ShPy4092; dmarc=pass (policy=quarantine) header.from=kernel.org; spf=pass (imf06.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787653665; b=7BBJWc9JimlT09eahFLAbif89rRl1pnvWQ7nZw8TSpsVAYG+nm68RuIBqBl/6YoxaEMnF9 Y4z7yNYUdLofs+1tsWNnr+HzQM4qgFk4HONn76TGcYPU72zEOdkhE1NFOug71ETmOUTFnV VYpEeQKLbMmXNks1e8qwcuLkA396D/E= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 4DBE3601E0; Tue, 25 Aug 2026 10:27:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E12F71F000E9; Tue, 25 Aug 2026 10:27:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787653664; bh=AmTIRDghT5aZb5UGuzctLRIrFioVqTHUxr0Sp616qgk=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=ShPy40928OrdedT4DDHV3NrG1zdtp2MAf0KfSjOriqJwJmwdEeebXZhjY+cP2bG2P DX24DZ2urmbwyD7akQHe+1sPrqr6SvuMKK2AK4T+u3tuHhzhSUtFVd3SlyGLPHZP7o uzFwIK7JLx1I4W702S7bhpj+DSm5lZETQqTbTsWzYkubU9wFJ64sUIFk4STrffBu5A sZBmGRklT2j1Em37fLf7jYrNhqyPiELdLO5jBis/uvJwAi1P+U9XCiDsHvtYDqLpu4 9ddSlAgY0CDyl4OLm66DB5z76DhHubcqRw7NHxEWgHWXTb81quv2FoS+kO52uUzrx5 L9srPGLmeeWEQ== Message-ID: Date: Tue, 25 Aug 2026 12:27:39 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/hugetlb: fix missing migratable flag on same-node hugetlb migration To: Wupeng Ma , muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, baolin.wang@linux.alibaba.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260707110254.3147686-1-mawupeng1@huawei.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: <20260707110254.3147686-1-mawupeng1@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: bpqwp7jqpeb8nzd53ucizzrzsiti4hix X-Rspamd-Queue-Id: 9A743180004 X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1787653665-898148 X-HE-Meta: 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 n9iBfRrb fhnvTDt/5DnA7oe6DZFFurPuPeGPXyTOAn4NC/KctYVkmZF0cQkhbZkWYq4MIXU+q9Sw628CEmqogvsh/TRuAKWxYX3gACT8UnfKV4f95L5928tBGWBndgIlI1p+7U77Yfde2E3j1YHE3wjDtz9ABYc0111959iZN/cMiRQgh+lhjv3O54Sb69puweEmaiE04hLrODWSYkW6gJ9qaKhvMcGcGFJnIWTcdeydAPr34EMtR0JMs5RfwHH63ZKD5Ia8VTcHskSFbrVi7y874TegSMgVUtQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/7/26 13:02, Wupeng Ma wrote: > Commit ba23f58de896 ("mm/migrate: don't call > folio_putback_active_hugetlb() on dst hugetlb folio") moved setting of > the migratable flag and active-list placement from > folio_putback_active_hugetlb(dst) into move_hugetlb_state(), so that > the freshly allocated destination folio is handled where allocation is > known to have succeeded. > > Unfortunately, the new code was appended after the existing > temporary-folio block in move_hugetlb_state(), which contains an early > return added earlier by commit 5af1ab1d24e08 ("mm/hugetlb: optimize > the surplus state transfer code in move_hugetlb_state()"): > > if (folio_test_hugetlb_temporary(new_folio)) { > ... > if (new_nid == old_nid) > return; <-- skips the new code > ... > } > > /* added by ba23f58 */ > folio_set_hugetlb_migratable(new_folio); > list_move_tail(&new_folio->lru, ...&h->hugepage_activelist); > > When the destination folio is temporary (i.e. the hugetlb pool was > exhausted and the migration callback fell back to > alloc_migrate_hugetlb_folio()) and the migration does not cross a > node -- the common case, and always true on a single-NUMA system -- > move_hugetlb_state() returns before setting the migratable flag or > adding the new folio to the active list. The destination folio is > then installed in the page table but cannot be isolated afterwards, > since folio_isolate_hugetlb() rejects folios without the migratable > flag; a subsequent soft-offline, hard-offline or memory-hotplug > offline of that folio fails with -EBUSY. > > This was reproduced on a single-NUMA arm64 VM: a second > MADV_SOFT_OFFLINE on an already-migrated hugetlb page returned EBUSY > and logged "hugepage isolation failed". > > Keep the surplus adjustment, which is the only part that depends on > the node crossing, guarded by `if (new_nid != old_nid)', while making > the migratable flag and active-list placement unconditional. This > preserves the cleanup intent of ba23f58 and closes the early-return > hole. > > Fixes: ba23f58de896 ("mm/migrate: don't call folio_putback_active_hugetlb() on dst hugetlb folio") Agreed, let's CC stable. > Signed-off-by: Wupeng Ma > --- > mm/hugetlb.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 571212b80835..cafadfdb63c0 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -7211,14 +7211,14 @@ void move_hugetlb_state(struct folio *old_folio, struct folio *new_folio, int re > * There is no need to transfer the per-node surplus state > * when we do not cross the node. > */ > - if (new_nid == old_nid) > - return; > - spin_lock_irq(&hugetlb_lock); > - if (h->surplus_huge_pages_node[old_nid]) { > - h->surplus_huge_pages_node[old_nid]--; > - h->surplus_huge_pages_node[new_nid]++; > + if (new_nid != old_nid) { > + spin_lock_irq(&hugetlb_lock); > + if (h->surplus_huge_pages_node[old_nid]) { > + h->surplus_huge_pages_node[old_nid]--; > + h->surplus_huge_pages_node[new_nid]++; > + } > + spin_unlock_irq(&hugetlb_lock); > } The return was really rather hidden, thanks! Can't we instead just turn the "return;" into a "continue;" ? -- Cheers, David