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Mon, 17 Aug 2026 15:58:05 +0000 (UTC) X-FDA: 85111217730.06.66D8FD3 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf31.hostedemail.com (Postfix) with ESMTP id D7B3A20004 for ; Mon, 17 Aug 2026 15:58:03 +0000 (UTC) Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=cqdcn0VG; spf=pass (imf31.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786982283; 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=nEGXB4A5gVD4yhh0v+vjyPfNcNQP55l8H/ySHn4DwGQ=; b=T2sa+XPSn6qJ75CaWd/ZZIdXOwUmTu4NpB29cB/+oANZht9CesPWkwfExdISTxXKtx5azP v8Ak4EfjNjEFvESIH2Unns+aX/b7bhjE4057weisMV+3ojhFqnwb1h3FvR4V4fuTlmPVbP h04BpTDxjoq6k4305iQxIsNWKJDVpcE= ARC-Authentication-Results: i=1; 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b=cqdcn0VGZiBw5cJDNbINfl/B+RMp0pLKQTMRA1L5+2zx0oxf/a3N+mJbpErITF0/X rfIYuYCcevchud8bbCcu3lHyMeFHE+OfB+o6SbNFSSOq0Ekil1yvNf/UhqW+2AV/fU 3HokIPyP6rwkKmZe6wf9CnXzmAnUzYltUBK5EuiXcRZrhqNNX5WqkqkKK21D1BsfqQ IYvG+KlxKMssGDnj4s6F9GKwC+Qe5Gd4/uu3yy0GCHinH82ZHABJiyaMR7sWNXNm7h xQrAHBYiMTzisUHg9v1gr5PYS5ymqJKncbGH4BELavH03xPLbBq5YlH8Q61nGLlKdN ufrfKPI5fO1DQ== Message-ID: Date: Mon, 17 Aug 2026 17:57:57 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4] mm: Use a folio in the softleaf_is_device_private path From: "David Hildenbrand (Arm)" To: Hongfu Li , akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hongfu Li References: <20260803031554.30421-1-hongfu.li@linux.dev> <3ae2f1e1-c784-44ed-9b2c-5edf5699d627@kernel.org> 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: <3ae2f1e1-c784-44ed-9b2c-5edf5699d627@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D7B3A20004 X-Stat-Signature: nhfptya7ddzhz787crazftnuapmfynhe X-Rspam-User: X-HE-Tag: 1786982283-701679 X-HE-Meta: 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 CpYxi/r/ w0mWYBRJdY0N4h5/hdHncbUT4mYNW44NYPw/+VqbBe5ZPliiBwQATofPQpPplKzKDFyrAYrn6m3MEO0YenLkDJn/wqcOyl6SIf9uMJR6Lzu6wbAualh5bzmfhiCQYZvXObo/H1XSYRXhj7TH0p+G1uwwKbEhRaigZlCDvWw5IV0v4zQ7a6pslqHfRcgdJehTmcCkLM7eRwut2scc8ASwfbnUqpYX4tzBpYcf/EwGleFdXwcwJ6W6No2+ZiRRRT5Ewcq/Lod9VNSsLs4jWACPVEvoSRh4BfLuVUWPC+/Z8vh5kYzEGh84OiakBxMdUvtfj9IvxfSGlHw7xHVU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/17/26 17:52, David Hildenbrand (Arm) wrote: > On 8/3/26 05:15, Hongfu Li wrote: >> From: Hongfu Li >> >> Use the folio APIs in the device_private migration path of do_swap_page(), >> replacing four calls to compound_head() with one. >> >> Signed-off-by: Hongfu Li >> Acked-by: David Hildenbrand (Arm) >> Reviewed-by: Lorenzo Stoakes (ARM) >> --- >> v4: >> - Drop the do_non_swap_page() extraction (patch 2/2 from v2) >> - Added Reviewed-by: Lorenzo Stoakes >> - Link to v2: https://lore.kernel.org/all/20260723030752.16979-1-hongfu.li@linux.dev/ >> v3: >> - Please ignore v3. >> v2: >> - Drop fault_folio, reuse the existing folio variable instead >> - Refresh commit messages >> - Update comment to use "folio" instead of "page" in the >> device_private path >> - Add Acked-by: David Hildenbrand >> - Add patch 2/2 to extract do_non_swap_page() from do_swap_page() >> - Link to v1: https://lore.kernel.org/all/20260721013347.65698-1-hongfu.li@linux.dev/ >> --- >> mm/memory.c | 11 ++++++----- >> 1 file changed, 6 insertions(+), 5 deletions(-) >> >> diff --git a/mm/memory.c b/mm/memory.c >> index 56b244552f13..bbb289ba09d3 100644 >> --- a/mm/memory.c >> +++ b/mm/memory.c >> @@ -4873,18 +4873,19 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) >> goto unlock; >> >> /* >> - * Get a page reference while we know the page can't be >> + * Get a folio reference while we know the folio can't be >> * freed. >> */ >> - if (trylock_page(vmf->page)) { >> + folio = page_folio(vmf->page); >> + if (folio_trylock(folio)) { >> struct dev_pagemap *pgmap; >> >> - get_page(vmf->page); >> + folio_get(folio); >> pte_unmap_unlock(vmf->pte, vmf->ptl); >> pgmap = page_pgmap(vmf->page); >> ret = pgmap->ops->migrate_to_ram(vmf); >> - unlock_page(vmf->page); >> - put_page(vmf->page); >> + folio_unlock(folio); >> + folio_put(folio); >> } else { >> pte_unmap(vmf->pte); >> softleaf_entry_wait_on_locked(entry, vmf->ptl); > > Okay, so this breaks the HMM selftests: > > # ok 30 hmm.hmm_device_private.migrate_anon_huge_fault > # # RUN hmm.hmm_device_private.migrate_partial_unmap_fault ... > [ 14.589125] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP > [ 14.589178] Modules linked in: test_hmm > [ 14.589203] CPU: 25 UID: 0 PID: 653 Comm: hmm-tests Not tainted 7.2.0-rc5+ #14 PREEMPT > [ 14.589243] Hardware name: linux,dummy-virt (DT) > [ 14.589268] pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) > [ 14.589300] pc : folio_unlock+0x78/0x88 > [ 14.589326] lr : folio_unlock+0x78/0x88 > [ 14.589349] sp : ffff80008284bb90 > [ 14.589368] x29: ffff80008284bb90 x28: ffff0000cc8ce180 x27: 0000000000000000 > [ 14.589406] x26: 0000000000000000 x25: ffff0000ca395dc0 x24: 0000000000000000 > [ 14.589447] x23: 0000000020100073 x22: ffff0000c23d35c0 x21: ffffffffbfff8000 > [ 14.589485] x20: ffffffffbfff8000 x19: ffff80008284bca0 x18: 0000000000000010 > [ 14.589523] x17: 3030303030303030 x16: 2066666666666666 x15: 6630303030303030 > [ 14.589562] x14: 0000000000000000 x13: 29296f696c6f6628 x12: 64656b636f6c5f74 > [ 14.589603] x11: fffffffffffc7100 x10: fffffffffffc70b0 x9 : ffffb0504ff88f70 > [ 14.589640] x8 : 3fffffffffffdfff x7 : ffff000c79b24bc0 x6 : 00000000000001a7 > [ 14.589680] x5 : ffff000c79b24bc0 x4 : 0000000000000000 x3 : 0000000000000000 > [ 14.589718] x2 : 0000000000000000 x1 : ffff0000cc8ce180 x0 : 000000000000003f > [ 14.589756] Call trace: > [ 14.589769] folio_unlock+0x78/0x88 (P) > [ 14.589792] do_swap_page+0xf40/0x1580 > [ 14.589815] __handle_mm_fault+0x648/0xe68 > [ 14.589838] handle_mm_fault+0x9c/0x330 > [ 14.589858] do_page_fault+0x268/0x7e0 > [ 14.589882] do_translation_fault+0x5c/0x80 > [ 14.589904] do_mem_abort+0x48/0xa0 > [ 14.589927] el0_da+0x38/0xd0 > [ 14.589948] el0t_64_sync_handler+0xd0/0xe8 > [ 14.589970] el0t_64_sync+0x198/0x1a0 > [ 14.589990] Code: d65f03c0 d000eec1 913c4021 94015993 (d4210000) > > I can only speculate that we need another > > folio = page_folio(vmf->page); > > after the migrate_to_ram() call. > > Let me try that real quick. > Yeah, that fixes it: diff --git a/mm/memory.c b/mm/memory.c index 4134ac607ee0..83d1a2be957c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4937,6 +4937,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); pgmap = page_pgmap(vmf->page); ret = pgmap->ops->migrate_to_ram(vmf); + folio = page_folio(vmf->page); folio_unlock(folio); folio_put(folio); } else { -- Cheers, David