From: Alistair Popple <apopple@nvidia.com>
To: linux-mm@kvack.org
Cc: david@fromorbit.com, dan.j.williams@intel.com,
jhubbard@nvidia.com, rcampbell@nvidia.com, willy@infradead.org,
jgg@nvidia.com, linux-fsdevel@vger.kernel.org, jack@suse.cz,
djwong@kernel.org, hch@lst.de, david@redhat.com,
ruansy.fnst@fujitsu.com, nvdimm@lists.linux.dev,
linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org,
jglisse@redhat.com, Alistair Popple <apopple@nvidia.com>
Subject: [RFC 09/10] mm/khugepage.c: Warn if trying to scan devmap pmd
Date: Thu, 11 Apr 2024 10:57:30 +1000 [thread overview]
Message-ID: <68427031c58645ba4b751022bf032ffd6b247427.1712796818.git-series.apopple@nvidia.com> (raw)
In-Reply-To: <cover.fe275e9819458a4bbb9451b888cafb88af8867d4.1712796818.git-series.apopple@nvidia.com>
The only user of devmap PTEs is FS DAX, and khugepaged should not be
scanning these VMAs. This is checked by calling
hugepage_vma_check. Therefore khugepaged should never encounter a
devmap PTE. Warn if this occurs.
Signed-off-by: Alistair Popple <apopple@nvidia.com>
---
Note this is a transitory patch to test the above assumption both at
runtime and during review. I will likely remove it as the whole thing
gets deleted when pXX_devmap is removed.
---
mm/khugepaged.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 88433cc..b10db15 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -955,7 +955,7 @@ static int find_pmd_or_thp_or_none(struct mm_struct *mm,
return SCAN_PMD_NULL;
if (pmd_trans_huge(pmde))
return SCAN_PMD_MAPPED;
- if (pmd_devmap(pmde))
+ if (WARN_ON_ONCE(pmd_devmap(pmde)))
return SCAN_PMD_NULL;
if (pmd_bad(pmde))
return SCAN_PMD_NULL;
--
git-series 0.9.1
next prev parent reply other threads:[~2024-04-11 0:58 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-11 0:57 [RFC 00/10] fs/dax: Fix FS DAX page reference counts Alistair Popple
2024-04-11 0:57 ` [RFC 01/10] mm/gup.c: Remove redundant check for PCI P2PDMA page Alistair Popple
2024-04-11 12:59 ` Jason Gunthorpe
2024-04-11 13:47 ` David Hildenbrand
2024-04-12 1:37 ` Alistair Popple
2024-04-11 0:57 ` [RFC 02/10] mm/hmm: Remove dead check for HugeTLB and FS DAX Alistair Popple
2024-04-11 12:25 ` Jason Gunthorpe
2024-04-11 13:37 ` Peter Xu
2024-04-12 1:28 ` Alistair Popple
2024-04-11 0:57 ` [RFC 03/10] pci/p2pdma: Don't initialise page refcount to one Alistair Popple
2024-04-11 12:29 ` Jason Gunthorpe
2024-04-12 5:40 ` Alistair Popple
2024-04-12 17:20 ` Dan Williams
2024-05-09 21:59 ` Logan Gunthorpe
2024-05-09 23:14 ` Alistair Popple
2024-04-11 0:57 ` [RFC 04/10] fs/dax: Don't track page mapping/index Alistair Popple
2024-04-12 15:22 ` Jan Kara
2024-04-12 17:31 ` Dan Williams
2024-04-15 7:03 ` Alistair Popple
2024-04-15 20:51 ` Dan Williams
2024-04-16 0:07 ` Alistair Popple
2024-04-16 0:36 ` Dan Williams
2024-04-12 17:21 ` Dan Williams
2024-04-11 0:57 ` [RFC 05/10] fs/dax: Refactor wait for dax idle page Alistair Popple
2024-04-12 14:37 ` Jan Kara
2024-04-13 20:19 ` John Hubbard
2024-04-15 8:41 ` Alistair Popple
2024-04-11 0:57 ` [RFC 06/10] fs/dax: Add dax_page_free callback Alistair Popple
2024-04-11 0:57 ` [RFC 07/10] mm: Allow compound zone device pages Alistair Popple
2024-04-11 12:32 ` Jason Gunthorpe
2024-04-11 14:10 ` Matthew Wilcox
2024-04-12 1:38 ` Alistair Popple
2024-04-11 0:57 ` [RFC 08/10] fs/dax: Properly refcount fs dax pages Alistair Popple
2024-04-11 0:57 ` Alistair Popple [this message]
2024-04-11 13:45 ` [RFC 09/10] mm/khugepage.c: Warn if trying to scan devmap pmd David Hildenbrand
2024-04-12 1:34 ` Alistair Popple
2024-04-11 0:57 ` [RFC 10/10] mm: Remove pXX_devmap Alistair Popple
2024-04-11 12:57 ` Jason Gunthorpe
2024-04-11 17:28 ` [RFC 00/10] fs/dax: Fix FS DAX page reference counts Dan Williams
2024-04-11 17:35 ` Jason Gunthorpe
2024-04-11 17:56 ` Dan Williams
2024-04-12 3:54 ` Alistair Popple
2024-04-12 6:55 ` Alistair Popple
2024-04-12 11:53 ` Jason Gunthorpe
2024-04-12 17:32 ` Dan Williams
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