| Message ID | 20180430175925.2657-4-toshi.kani@hpe.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, 2018-04-30 at 11:59 -0600, Toshi Kani wrote: > 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: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") > Reported-by: Joerg Roedel <joro@8bytes.org> Hi Joerg, Does it solve your problem? Let me know if you have any issue with the series. Thanks, -Toshi
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 816fd41ee854..809115150d8b 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -715,6 +715,7 @@ 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. @@ -784,4 +785,22 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) return 1; } + +#else /* !CONFIG_X86_64 */ + +int pud_free_pmd_page(pud_t *pud, unsigned long addr) +{ + 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, unsigned long addr) +{ + return pmd_none(*pmd); +} + +#endif /* CONFIG_X86_64 */ #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
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: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") Reported-by: Joerg Roedel <joro@8bytes.org> Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: <stable@vger.kernel.org> --- arch/x86/mm/pgtable.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)