[RFC 09/10] mm/khugepage.c: Warn if trying to scan devmap pmd

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


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@xxxxxxxxxx>


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

[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux