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a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1734511762; 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; bh=5iqMZVMLTA2y+zuzfghDZHhbV9cVfoChhtJCRh6bKtY=; b=I96fcUqNk9t4bIEEV6SUHXxoRlP2lo93ynMx4h7YrDvt6nIjvRlQgB1wUP5zUNkTdG2xFx NiyM1S+OTPwcDRbktdiyEvL9kvFaSOFHy7zNKzRLITR00pi1TMDZAa0fA/RS8OUCXotSc2 fligdnFIibB7ZiNPNZsKfdBBhxPR0Cg= Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2F8B41063; Wed, 18 Dec 2024 00:50:19 -0800 (PST) Received: from [10.162.42.42] (K4MQJ0H1H2.blr.arm.com [10.162.42.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D09953F7B4; Wed, 18 Dec 2024 00:49:40 -0800 (PST) Message-ID: <1311738e-c9cc-4667-a758-f20d770ea329@arm.com> Date: Wed, 18 Dec 2024 14:19:37 +0530 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 06/12] khugepaged: Generalize __collapse_huge_page_copy_failed() To: Ryan Roberts , akpm@linux-foundation.org, david@redhat.com, willy@infradead.org, kirill.shutemov@linux.intel.com Cc: anshuman.khandual@arm.com, catalin.marinas@arm.com, cl@gentwo.org, vbabka@suse.cz, mhocko@suse.com, apopple@nvidia.com, dave.hansen@linux.intel.com, will@kernel.org, baohua@kernel.org, jack@suse.cz, srivatsa@csail.mit.edu, haowenchao22@gmail.com, hughd@google.com, aneesh.kumar@kernel.org, yang@os.amperecomputing.com, peterx@redhat.com, ioworker0@gmail.com, wangkefeng.wang@huawei.com, ziy@nvidia.com, jglisse@google.com, surenb@google.com, vishal.moola@gmail.com, zokeefe@google.com, zhengqi.arch@bytedance.com, jhubbard@nvidia.com, 21cnbao@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20241216165105.56185-1-dev.jain@arm.com> <20241216165105.56185-7-dev.jain@arm.com> <4a2554ad-c204-4350-8898-545c1da124bb@arm.com> Content-Language: en-US From: Dev Jain In-Reply-To: <4a2554ad-c204-4350-8898-545c1da124bb@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 056F6160009 X-Stat-Signature: i7ngj3fh8f3k43b6rd9whdo6mfnnn53s X-Rspam-User: X-HE-Tag: 1734511770-865278 X-HE-Meta: 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 t9Kom+7U bmC5t4z344xAbU0RUdKJ9RPBZbaOlwKQUtLtBHhp48ivxxZQdzT0OQr6fZJU4C0pyjEBlnAbnUV5XDpgIAQcD0OqWWOEoKF/CoHI0wnRsIrwKFbNxtwBjrL7pJLafRnxY+ARECAYM8KaaS4E5CrfmVjZUTNTkZ42Pzquqz6E66dD+G0aaqfBTltdB+Q1eCgIK0TpcNz2+3jTU0P33fMOspQ7+KyciIs2GIvidffQmWq0ZwZgakY8z5X9RLhsE4TYvrKr77PJy16Be3MEAkQN8yygTASqLPRxe2SLoFR52cP6+JWUUOqaBzdIqbjNBSaCyVjKSatmJm1g6sNEEPAY7vZQLHXi3QQPG09LJ7IPic+Jk1lwKcqoA7hk0knKdqzMM7ediV3WZW4eycsiiX/by8dPfC6n2ATPkLbsFucy//eteuvw3Fr8+BYs7A230Gl/qFSxi 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 17/12/24 10:52 pm, Ryan Roberts wrote: > On 16/12/2024 16:50, Dev Jain wrote: >> Upon failure, we repopulate the PMD in case of PMD-THP collapse. Hence, make >> this logic specific for PMD case. >> >> Signed-off-by: Dev Jain >> --- >> mm/khugepaged.c | 14 ++++++++------ >> 1 file changed, 8 insertions(+), 6 deletions(-) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index de044b1f83d4..886c76816963 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -766,7 +766,7 @@ static void __collapse_huge_page_copy_failed(pte_t *pte, >> pmd_t *pmd, >> pmd_t orig_pmd, >> struct vm_area_struct *vma, >> - struct list_head *compound_pagelist) >> + struct list_head *compound_pagelist, int order) > nit: suggest putting order on its own line. > >> { >> spinlock_t *pmd_ptl; >> >> @@ -776,14 +776,16 @@ static void __collapse_huge_page_copy_failed(pte_t *pte, >> * pages. Since pages are still isolated and locked here, >> * acquiring anon_vma_lock_write is unnecessary. >> */ >> - pmd_ptl = pmd_lock(vma->vm_mm, pmd); >> - pmd_populate(vma->vm_mm, pmd, pmd_pgtable(orig_pmd)); >> - spin_unlock(pmd_ptl); >> + if (order == HPAGE_PMD_ORDER) { >> + pmd_ptl = pmd_lock(vma->vm_mm, pmd); >> + pmd_populate(vma->vm_mm, pmd, pmd_pgtable(orig_pmd)); >> + spin_unlock(pmd_ptl); >> + } >> /* >> * Release both raw and compound pages isolated >> * in __collapse_huge_page_isolate. >> */ >> - release_pte_pages(pte, pte + HPAGE_PMD_NR, compound_pagelist); >> + release_pte_pages(pte, pte + (1UL << order), compound_pagelist); >> } > Given this function is clearly so geared towards re-establishing the pmd, given > that it takes the *pmd and orig_pmd as params, and given that in the > non-pmd-order case, we only call through to release_pte_pages(), I wonder if > it's better to make the decision at a higher level and either call this function > or release_pte_pages() directly? No strong opinion, just looks a bit weird at > the moment. Makes sense, we can probably get rid of this function and let the caller call reestablish_pmd() or something for the PMD case. > >> >> /* >> @@ -834,7 +836,7 @@ static int __collapse_huge_page_copy(pte_t *pte, struct folio *folio, >> compound_pagelist); >> else >> __collapse_huge_page_copy_failed(pte, pmd, orig_pmd, vma, >> - compound_pagelist); >> + compound_pagelist, order); >> >> return result; >> }