diff mbox

[v2,1/3] x86/mm: disable ioremap free page handling on x86-PAE

Message ID 20180515213931.23885-2-toshi.kani@hpe.com (mailing list archive)
State New, archived
Headers show

Commit Message

Kani, Toshi May 15, 2018, 9:39 p.m. UTC 
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(+)

Comments

kernel test robot May 16, 2018, 11 a.m. UTC | #1 
Hi Toshi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on v4.17-rc5 next-20180515]
[cannot apply to tip/x86/core]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Toshi-Kani/fix-free-pmd-pte-page-handlings-on-x86/20180516-183317
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
config: i386-randconfig-x013-201819 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

Note: the linux-review/Toshi-Kani/fix-free-pmd-pte-page-handlings-on-x86/20180516-183317 HEAD 93944422fcef9bfadf22e345c1d7a34723cc3203 builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

>> arch/x86/mm/pgtable.c:757:5: error: conflicting types for 'pud_free_pmd_page'
    int pud_free_pmd_page(pud_t *pud, unsigned long addr)
        ^~~~~~~~~~~~~~~~~
   In file included from arch/x86/include/asm/pgtable.h:1301:0,
                    from include/linux/memremap.h:8,
                    from include/linux/mm.h:27,
                    from arch/x86/mm/pgtable.c:2:
   include/asm-generic/pgtable.h:1022:5: note: previous declaration of 'pud_free_pmd_page' was here
    int pud_free_pmd_page(pud_t *pud);
        ^~~~~~~~~~~~~~~~~
>> arch/x86/mm/pgtable.c:766:5: error: conflicting types for 'pmd_free_pte_page'
    int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
        ^~~~~~~~~~~~~~~~~
   In file included from arch/x86/include/asm/pgtable.h:1301:0,
                    from include/linux/memremap.h:8,
                    from include/linux/mm.h:27,
                    from arch/x86/mm/pgtable.c:2:
   include/asm-generic/pgtable.h:1023:5: note: previous declaration of 'pmd_free_pte_page' was here
    int pmd_free_pte_page(pmd_t *pmd);
        ^~~~~~~~~~~~~~~~~

vim +/pud_free_pmd_page +757 arch/x86/mm/pgtable.c

   756	
 > 757	int pud_free_pmd_page(pud_t *pud, unsigned long addr)
   758	{
   759		return pud_none(*pud);
   760	}
   761	
   762	/*
   763	 * Disable free page handling on x86-PAE. This assures that ioremap()
   764	 * does not update sync'd pmd entries. See vmalloc_sync_one().
   765	 */
 > 766	int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
   767	{
   768		return pmd_none(*pmd);
   769	}
   770	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
Kani, Toshi May 16, 2018, 2:05 p.m. UTC | #2 
On Wed, 2018-05-16 at 19:00 +0800, kbuild test robot wrote:
> Hi Toshi,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on arm64/for-next/core]
> [also build test ERROR on v4.17-rc5 next-20180515]
> [cannot apply to tip/x86/core]
> [if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Toshi-Kani/fix-free-pmd-pte-page-handlings-on-x86/20180516-183317
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
> config: i386-randconfig-x013-201819 (attached as .config)
> compiler: gcc-7 (Debian 7.3.0-16) 7.3.0
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> Note: the linux-review/Toshi-Kani/fix-free-pmd-pte-page-handlings-on-x86/20180516-183317 HEAD 93944422fcef9bfadf22e345c1d7a34723cc3203 builds fine.
>       It only hurts bisectibility.
> 
> All errors (new ones prefixed by >>):
> 
> > > arch/x86/mm/pgtable.c:757:5: error: conflicting types for 'pud_free_pmd_page'
> 
>     int pud_free_pmd_page(pud_t *pud, unsigned long addr)
>         ^~~~~~~~~~~~~~~~~

Thanks for catching this!  Patch reordering caused this.  Will fix.
-Toshi
diff mbox

Patch

diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index ffc8c13c50e4..08cdd7c13619 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.
@@ -762,4 +763,22 @@  int pmd_free_pte_page(pmd_t *pmd)
 
 	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 */