From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 90BE22C11CF; Sun, 31 May 2026 20:18:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780258711; cv=none; b=MPojufarQxqaiv64QG16imuQ+R5394WsBVR8JJ78qt5xgLEQZ9uKrdoFsNAVOhlG9aKL1fVBcmBUL/XF+ycXLR6dLbXIFaJHwHMQHIddfHE5xeRCcdnyURzJhilMoeoK9xTaUtGpuyvYF8DYiNWaJm5YQhVss+/oGycqm7IjfSY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780258711; c=relaxed/simple; bh=v0oQkrVLLFALNACmL0/uM2zUk+XUViv3+vvFdT8niOg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TZ4vKysRnYgPhdIV+Bo2HOJagvAYCzrHy9HGaJEFYNIK6pVo2HEPvNEMU4l7UqlXEMA3G+d5LKdLw/ualsLTz4tfujVdxwDHRpkD/TzspfNgwJIj1cJdY++HnchkH9QzGAhl0nGIQy9hRg6E9t+IJeLLnej3xGEqQsUIVpYqo8M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JuraNp+n; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JuraNp+n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33C6F1F00893; Sun, 31 May 2026 20:18:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780258710; bh=0oJD4MFiWJKAvd1Y1uNLeroAJlcqeh9bsxIYTnCdu2s=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=JuraNp+nvV/FZss9GmTbljR4/DaII9mHJtQWBFTelkHUiQcSU7fCvzP37CNPGJRhd C/c2V+VkfbeA3CCEG4w/P2FdKzN8IsPUxVQ4ivVSQ2cwIwaGecFeKOHs1dDm8WoeiH UVYJkvkT1S4g/6F7fN53c/ZrV5QJ8bKdLPvZoRtxdOCQlIcgeDl60GCrcTuPwUvo3O +32fw8ZaPtMXA7tXYenmVzm1czbVytuhRVfUj6f8we9GNSMDz1bGIsbGIb56elCa6h U72rn2bjrd7apVIWAtaSfa14kzTxvTV5ZKJly8SPLWgJ4QSbQUhh9XCdSJg3pvHHVV rtBr6ac1LFYDg== Message-ID: Date: Sun, 31 May 2026 22:18:16 +0200 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 mm-unstable v18 10/14] mm/khugepaged: introduce collapse_allowable_orders helper function To: Nico Pache , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Cc: aarcange@redhat.com, akpm@linux-foundation.org, anshuman.khandual@arm.com, apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, byungchul@sk.com, catalin.marinas@arm.com, cl@gentwo.org, corbet@lwn.net, dave.hansen@linux.intel.com, dev.jain@arm.com, gourry@gourry.net, hannes@cmpxchg.org, hughd@google.com, jack@suse.cz, jackmanb@google.com, jannh@google.com, jglisse@google.com, joshua.hahnjy@gmail.com, kas@kernel.org, lance.yang@linux.dev, liam@infradead.org, ljs@kernel.org, mathieu.desnoyers@efficios.com, matthew.brost@intel.com, mhiramat@kernel.org, mhocko@suse.com, peterx@redhat.com, pfalcato@suse.de, rakie.kim@sk.com, raquini@redhat.com, rdunlap@infradead.org, richard.weiyang@gmail.com, rientjes@google.com, rostedt@goodmis.org, rppt@kernel.org, ryan.roberts@arm.com, shivankg@amd.com, sunnanyong@huawei.com, surenb@google.com, thomas.hellstrom@linux.intel.com, tiwai@suse.de, usamaarif642@gmail.com, vbabka@suse.cz, vishal.moola@gmail.com, wangkefeng.wang@huawei.com, will@kernel.org, willy@infradead.org, yang@os.amperecomputing.com, ying.huang@linux.alibaba.com, ziy@nvidia.com, zokeefe@google.com References: <20260522150009.121603-1-npache@redhat.com> <20260522150009.121603-11-npache@redhat.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/22/26 17:00, Nico Pache wrote: > Add collapse_allowable_orders() to generalize THP order eligibility. The > function determines which THP orders are permitted based on collapse > context (khugepaged vs madv_collapse). > > This consolidates collapse configuration logic and provides a clean > interface for future mTHP collapse support where the orders may be > different. It would have been good to describe here that, for now, it only ever returns PMDs, and that it will be extended next. Logically, this patch belongs to #12, not #11 ... so seeing it before #11 was a bit ... and there, it is clear that we don't even want to know the orders? So can we just call this function "collapse_possible" and make it return a boolean? > > Reviewed-by: Baolin Wang > Signed-off-by: Nico Pache > --- > mm/khugepaged.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index 4534025bc81d..64ceebc9d8a7 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -552,12 +552,21 @@ void __khugepaged_enter(struct mm_struct *mm) > wake_up_interruptible(&khugepaged_wait); > } > > +/* Check what orders are allowed based on the vma and collapse type */ > +static unsigned long collapse_allowable_orders(struct vm_area_struct *vma, > + vm_flags_t vm_flags, enum tva_type tva_flags) > +{ > + unsigned long orders = BIT(HPAGE_PMD_ORDER); > + > + return thp_vma_allowable_orders(vma, vm_flags, tva_flags, orders); > +} > + > void khugepaged_enter_vma(struct vm_area_struct *vma, > vm_flags_t vm_flags) > { > if (!mm_flags_test(MMF_VM_HUGEPAGE, vma->vm_mm) && > hugepage_pmd_enabled()) { > - if (thp_vma_allowable_order(vma, vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) > + if (collapse_allowable_orders(vma, vm_flags, TVA_KHUGEPAGED)) > __khugepaged_enter(vma->vm_mm); > } > } > @@ -2680,7 +2689,7 @@ static void collapse_scan_mm_slot(unsigned int progress_max, > cc->progress++; > break; > } > - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_KHUGEPAGED, PMD_ORDER)) { > + if (!collapse_allowable_orders(vma, vma->vm_flags, TVA_KHUGEPAGED)) { > cc->progress++; > continue; > } > @@ -2989,7 +2998,7 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, > BUG_ON(vma->vm_start > start); > BUG_ON(vma->vm_end < end); > > - if (!thp_vma_allowable_order(vma, vma->vm_flags, TVA_FORCED_COLLAPSE, PMD_ORDER)) > + if (!collapse_allowable_orders(vma, vma->vm_flags, TVA_FORCED_COLLAPSE)) > return -EINVAL; > > cc = kmalloc_obj(*cc); Having a simple static bool collapse_possible(...) { return collapse_allowable_orders(...) } Would make the above slightly more readable. Acked-by: David Hildenbrand (Arm) -- Cheers, David