Commit 2ca715a1 authored by Toshi Kani's avatar Toshi Kani Committed by Greg Kroah-Hartman
Browse files

x86/mm: Disable ioremap free page handling on x86-PAE

commit f967db0b upstream.

ioremap() supports pmd mappings on x86-PAE.  However, kernel's pmd
tables are not shared among processes on x86-PAE.  Therefore, any
update to sync'd pmd entries need re-syncing.  Freeing a pte page
also leads to a vmalloc fault and hits the BUG_ON in vmalloc_sync_one().

Disable free page handling on x86-PAE.  pud_free_pmd_page() and
pmd_free_pte_page() simply return 0 if a given pud/pmd entry is present.
This assures that ioremap() does not update sync'd pmd entries at the
cost of falling back to pte mappings.

Fixes: 28ee90fe

 ("x86/mm: implement free pmd/pte page interfaces")
Reported-by: default avatarJoerg Roedel <>
Signed-off-by: default avatarToshi Kani <>
Signed-off-by: default avatarThomas Gleixner <>
Cc: Andrew Morton <>
Cc: Michal Hocko <>
Cc: "H. Peter Anvin" <>
Cc: <>

Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 0ae4fd90
......@@ -719,6 +719,7 @@ int pmd_clear_huge(pmd_t *pmd)
return 0;
#ifdef CONFIG_X86_64
* pud_free_pmd_page - Clear pud entry and free pmd page.
* @pud: Pointer to a PUD.
......@@ -766,4 +767,22 @@ int pmd_free_pte_page(pmd_t *pmd)
return 1;
#else /* !CONFIG_X86_64 */
int pud_free_pmd_page(pud_t *pud)
return pud_none(*pud);
* Disable free page handling on x86-PAE. This assures that ioremap()
* does not update sync'd pmd entries. See vmalloc_sync_one().
int pmd_free_pte_page(pmd_t *pmd)
return pmd_none(*pmd);
#endif /* CONFIG_X86_64 */
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