From: David Hildenbrand <david@redhat.com>
To: Alistair Popple <apopple@nvidia.com>, akpm@linux-foundation.org
Cc: linux-mm@kvack.org, gerald.schaefer@linux.ibm.com,
dan.j.williams@intel.com, jgg@ziepe.ca, willy@infradead.org,
linux-kernel@vger.kernel.org, nvdimm@lists.linux.dev,
linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-xfs@vger.kernel.org, jhubbard@nvidia.com, hch@lst.de,
zhang.lyra@gmail.com, debug@rivosinc.com, bjorn@kernel.org,
balbirs@nvidia.com, lorenzo.stoakes@oracle.com,
linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev,
linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
linux-cxl@vger.kernel.org, dri-devel@lists.freedesktop.org,
John@Groves.net, m.szyprowski@samsung.com,
Jason Gunthorpe <jgg@nvidia.com>
Subject: Re: [PATCH v2 08/14] mm/khugepaged: Remove redundant pmd_devmap() check
Date: Tue, 17 Jun 2025 11:44:30 +0200 [thread overview]
Message-ID: <31bdbfcf-bbfa-46b7-a427-806d42d88cec@redhat.com> (raw)
In-Reply-To: <d4aa84277015fe21978232ed4ac91bd7270e9ee0.1750075065.git-series.apopple@nvidia.com>
On 16.06.25 13:58, Alistair Popple wrote:
> The only users of pmd_devmap were device dax and fs dax. The check for
> pmd_devmap() in check_pmd_state() is therefore redundant as callers
> explicitly check for is_zone_device_page(), so this check can be dropped.
>
Looking again, is this true?
If we return "SCAN_SUCCEED", we assume there is a page table there that
we can map and walk.
But I assume we can drop that check because nobody will ever set
pmd_devmap() anymore?
So likely just the description+sibject of this patch should be adjusted.
FWIW, I think check_pmd_state() should be changed to work on pmd_leaf()
etc, but that's something for another day.
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2025-06-17 9:44 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-16 11:58 [PATCH v2 00/14] mm: Remove pXX_devmap page table bit and pfn_t type Alistair Popple
2025-06-16 11:58 ` [PATCH v2 01/14] mm: Convert pXd_devmap checks to vma_is_dax Alistair Popple
2025-06-17 9:19 ` David Hildenbrand
2025-06-19 8:40 ` Alistair Popple
2025-06-16 11:58 ` [PATCH v2 02/14] mm: Filter zone device pages returned from folio_walk_start() Alistair Popple
2025-06-17 9:25 ` David Hildenbrand
2025-06-17 9:30 ` David Hildenbrand
2025-06-19 0:41 ` Alistair Popple
2025-06-16 11:58 ` [PATCH v2 03/14] mm: Convert vmf_insert_mixed() from using pte_devmap to pte_special Alistair Popple
2025-06-17 9:49 ` David Hildenbrand
2025-06-18 9:31 ` David Hildenbrand
2025-06-16 11:58 ` [PATCH v2 04/14] mm: Remove remaining uses of PFN_DEV Alistair Popple
2025-06-16 11:58 ` [PATCH v2 05/14] mm/gup: Remove pXX_devmap usage from get_user_pages() Alistair Popple
2025-06-16 11:58 ` [PATCH v2 06/14] mm/huge_memory: Remove pXd_devmap usage from insert_pXd_pfn() Alistair Popple
2025-06-17 9:49 ` David Hildenbrand
2025-06-19 8:52 ` Alistair Popple
2025-06-16 11:58 ` [PATCH v2 07/14] mm: Remove redundant pXd_devmap calls Alistair Popple
2025-06-16 11:58 ` [PATCH v2 08/14] mm/khugepaged: Remove redundant pmd_devmap() check Alistair Popple
2025-06-17 9:44 ` David Hildenbrand [this message]
2025-06-19 7:56 ` Alistair Popple
2025-06-16 11:58 ` [PATCH v2 09/14] powerpc: Remove checks for devmap pages and PMDs/PUDs Alistair Popple
2025-06-17 9:37 ` David Hildenbrand
2025-06-16 11:58 ` [PATCH v2 10/14] fs/dax: Remove FS_DAX_LIMITED config option Alistair Popple
2025-06-17 9:37 ` David Hildenbrand
2025-06-16 11:58 ` [PATCH v2 11/14] mm: Remove devmap related functions and page table bits Alistair Popple
2025-06-17 9:36 ` David Hildenbrand
2025-06-16 11:58 ` [PATCH v2 12/14] mm: Remove PFN_MAP, PFN_SPECIAL, PFN_SG_CHAIN and PFN_SG_LAST Alistair Popple
2025-06-16 11:58 ` [PATCH v2 13/14] mm: Remove callers of pfn_t functionality Alistair Popple
2025-06-17 9:35 ` David Hildenbrand
2025-06-16 11:58 ` [PATCH v2 14/14] mm/memremap: Remove unused devmap_managed_key Alistair Popple
2025-06-17 9:34 ` David Hildenbrand
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