From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 58FD9223DFB; Wed, 23 Apr 2025 06:49:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.110 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745390979; cv=none; b=XHZB4jdAhzanslUF368wKPKyG9ZXNTUBWWozfJYdhKsJYjczL0kp/7BUSvAp2DvOBonrd7Wj+Kl/DjWrGEoO6uO9PRM6dajGEgGeC+zjbEhDq5rDvQ0X6BqhktdC2Up5Wizx/EIyo+KhbeEYCzrQZMn8NA6Pcjkk++/+9yrEMlM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745390979; c=relaxed/simple; bh=lUuKd3ibErYYayL//vzQvPhmAbfz1EX03LJr3UQb6yU=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UwuBaihxp87aEG3inT6hia6uanKUc2bk8XrodeIE8W5uioh+RjhtiHJXqs1pThvi7Jvn2FTrspoW4ePYwZYxynr98hKhSNnHueW5Z7GsMglLdde244PIMhsc2D3HkcOwSY6GhsN/o8blxIVXdZkyObbMZpLU+CJi1W5JSLNJl2I= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=szjf+beS; arc=none smtp.client-ip=115.124.30.110 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="szjf+beS" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1745390967; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=JGm9lYL8xvhbTj7FN+hg66vA+WW9yw+RDmjxEEjhhuQ=; b=szjf+beSqHvZ4+g3t4cv+4oZdDBgNPLWxKUB8YHjKzNnALpNIxRsLbkC6Ch1yMee9MD03ClrtYkS4/yzAP/kJfofzEwtXeCPbXTePp4ql5pxoZIBXB7d46QmerHCRvPPxdpLUngYTkABtFF/xPdm/2iwCpNZB+dKiE/hXRS+mds= Received: from 30.74.144.121(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0WXtRz4h_1745390641 cluster:ay36) by smtp.aliyun-inc.com; Wed, 23 Apr 2025 14:44:02 +0800 Message-ID: Date: Wed, 23 Apr 2025 14:44:01 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 01/12] introduce khugepaged_collapse_single_pmd to unify khugepaged and madvise_collapse To: Nico Pache , linux-mm@kvack.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, corbet@lwn.net, rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, david@redhat.com, baohua@kernel.org, ryan.roberts@arm.com, willy@infradead.org, peterx@redhat.com, ziy@nvidia.com, wangkefeng.wang@huawei.com, usamaarif642@gmail.com, sunnanyong@huawei.com, vishal.moola@gmail.com, thomas.hellstrom@linux.intel.com, yang@os.amperecomputing.com, kirill.shutemov@linux.intel.com, aarcange@redhat.com, raquini@redhat.com, dev.jain@arm.com, anshuman.khandual@arm.com, catalin.marinas@arm.com, tiwai@suse.de, will@kernel.org, dave.hansen@linux.intel.com, jack@suse.cz, cl@gentwo.org, jglisse@google.com, surenb@google.com, zokeefe@google.com, hannes@cmpxchg.org, rientjes@google.com, mhocko@suse.com, rdunlap@infradead.org References: <20250417000238.74567-1-npache@redhat.com> <20250417000238.74567-2-npache@redhat.com> From: Baolin Wang In-Reply-To: <20250417000238.74567-2-npache@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2025/4/17 08:02, Nico Pache wrote: > The khugepaged daemon and madvise_collapse have two different > implementations that do almost the same thing. > > Create khugepaged_collapse_single_pmd to increase code > reuse and create an entry point for future khugepaged changes. > > Refactor madvise_collapse and khugepaged_scan_mm_slot to use > the new khugepaged_collapse_single_pmd function. > > Signed-off-by: Nico Pache Can you add a prefix 'khugepaged:' for the subject line? > --- > mm/khugepaged.c | 92 ++++++++++++++++++++++++------------------------- > 1 file changed, 46 insertions(+), 46 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index b8838ba8207a..cecadc4239e7 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -2363,6 +2363,48 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr, > } > #endif > > +/* > + * Try to collapse a single PMD starting at a PMD aligned addr, and return > + * the results. > + */ > +static int khugepaged_collapse_single_pmd(unsigned long addr, > + struct vm_area_struct *vma, bool *mmap_locked, > + struct collapse_control *cc) > +{ > + int result = SCAN_FAIL; > + struct mm_struct *mm = vma->vm_mm; > + unsigned long tva_flags = cc->is_khugepaged ? TVA_ENFORCE_SYSFS : 0; > + > + if (thp_vma_allowable_order(vma, vma->vm_flags, > + tva_flags, PMD_ORDER)) { We've already checked the thp_vma_allowable_order() before calling this function, why check again? > + if (IS_ENABLED(CONFIG_SHMEM) && !vma_is_anonymous(vma)) { > + struct file *file = get_file(vma->vm_file); > + pgoff_t pgoff = linear_page_index(vma, addr); > + > + mmap_read_unlock(mm); > + *mmap_locked = false; > + result = hpage_collapse_scan_file(mm, addr, file, pgoff, > + cc); > + fput(file); > + if (result == SCAN_PTE_MAPPED_HUGEPAGE) { > + mmap_read_lock(mm); > + if (hpage_collapse_test_exit_or_disable(mm)) > + goto end; > + result = collapse_pte_mapped_thp(mm, addr, > + !cc->is_khugepaged); why drop the following check? if (*result == SCAN_PMD_MAPPED) *result = SCAN_SUCCEED; > + mmap_read_unlock(mm); > + } > + } else { > + result = hpage_collapse_scan_pmd(mm, vma, addr, > + mmap_locked, cc); > + } > + if (cc->is_khugepaged && result == SCAN_SUCCEED) > + ++khugepaged_pages_collapsed; > + } > +end: > + return result; > +} > + > static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, > struct collapse_control *cc) > __releases(&khugepaged_mm_lock) > @@ -2437,33 +2479,9 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, > VM_BUG_ON(khugepaged_scan.address < hstart || > khugepaged_scan.address + HPAGE_PMD_SIZE > > hend); > - if (IS_ENABLED(CONFIG_SHMEM) && !vma_is_anonymous(vma)) { > - struct file *file = get_file(vma->vm_file); > - pgoff_t pgoff = linear_page_index(vma, > - khugepaged_scan.address); > > - mmap_read_unlock(mm); > - mmap_locked = false; > - *result = hpage_collapse_scan_file(mm, > - khugepaged_scan.address, file, pgoff, cc); > - fput(file); > - if (*result == SCAN_PTE_MAPPED_HUGEPAGE) { > - mmap_read_lock(mm); > - if (hpage_collapse_test_exit_or_disable(mm)) > - goto breakouterloop; > - *result = collapse_pte_mapped_thp(mm, > - khugepaged_scan.address, false); > - if (*result == SCAN_PMD_MAPPED) > - *result = SCAN_SUCCEED; > - mmap_read_unlock(mm); > - } > - } else { > - *result = hpage_collapse_scan_pmd(mm, vma, > - khugepaged_scan.address, &mmap_locked, cc); > - } > - > - if (*result == SCAN_SUCCEED) > - ++khugepaged_pages_collapsed; > + *result = khugepaged_collapse_single_pmd(khugepaged_scan.address, > + vma, &mmap_locked, cc); If the khugepaged_collapse_single_pmd() returns a failure caused by hpage_collapse_test_exit_or_disable(), we should break out of the loop according to the original logic. But you've changed the action in this patch, is this intentional? > > /* move to next address */ > khugepaged_scan.address += HPAGE_PMD_SIZE; > @@ -2783,36 +2801,18 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev, > mmap_assert_locked(mm); > memset(cc->node_load, 0, sizeof(cc->node_load)); > nodes_clear(cc->alloc_nmask); > - if (IS_ENABLED(CONFIG_SHMEM) && !vma_is_anonymous(vma)) { > - struct file *file = get_file(vma->vm_file); > - pgoff_t pgoff = linear_page_index(vma, addr); > > - mmap_read_unlock(mm); > - mmap_locked = false; > - result = hpage_collapse_scan_file(mm, addr, file, pgoff, > - cc); > - fput(file); > - } else { > - result = hpage_collapse_scan_pmd(mm, vma, addr, > - &mmap_locked, cc); > - } > + result = khugepaged_collapse_single_pmd(addr, vma, &mmap_locked, cc); > + > if (!mmap_locked) > *prev = NULL; /* Tell caller we dropped mmap_lock */ > > -handle_result: > switch (result) { > case SCAN_SUCCEED: > case SCAN_PMD_MAPPED: > ++thps; > break; > case SCAN_PTE_MAPPED_HUGEPAGE: > - BUG_ON(mmap_locked); > - BUG_ON(*prev); > - mmap_read_lock(mm); > - result = collapse_pte_mapped_thp(mm, addr, true); > - mmap_read_unlock(mm); > - goto handle_result; > - /* Whitelisted set of results where continuing OK */ > case SCAN_PMD_NULL: > case SCAN_PTE_NON_PRESENT: > case SCAN_PTE_UFFD_WP: