Re: [PATCH v2 2/2] x86/mm: implement free pmd/pte page interfaces
From: Chintan Pandya <hidden>
Date: 2018-03-15 07:39:36
Also in:
linux-arm-kernel, lkml, stable
On 3/14/2018 11:31 PM, Toshi Kani wrote:
quoted hunk ↗ jump to hunk
Implement pud_free_pmd_page() and pmd_free_pte_page() on x86, which clear a given pud/pmd entry and free up lower level page table(s). Address range associated with the pud/pmd entry must have been purged by INVLPG. fixes: e61ce6ade404e ("mm: change ioremap to set up huge I/O mappings") Signed-off-by: Toshi Kani <redacted> Cc: Michal Hocko <mhocko@suse.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Thomas Gleixner <redacted> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Borislav Petkov <redacted> Cc: Matthew Wilcox <willy@infradead.org> Cc: <redacted> --- arch/x86/mm/pgtable.c | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-)diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 1eed7ed518e6..34cda7e0551b 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c@@ -712,7 +712,22 @@ int pmd_clear_huge(pmd_t *pmd) */ int pud_free_pmd_page(pud_t *pud) { - return pud_none(*pud); + pmd_t *pmd; + int i; + + if (pud_none(*pud)) + return 1; + + pmd = (pmd_t *)pud_page_vaddr(*pud); + + for (i = 0; i < PTRS_PER_PMD; i++) + if (!pmd_free_pte_page(&pmd[i]))
This is forced action and no optional. Also, pmd_free_pte_page() doesn't return 0 in any case. So, you may remove _if_ ?
quoted hunk ↗ jump to hunk
+ return 0; + + pud_clear(pud); + free_page((unsigned long)pmd); + + return 1; } /**@@ -724,6 +739,15 @@ int pud_free_pmd_page(pud_t *pud) */ int pmd_free_pte_page(pmd_t *pmd) { - return pmd_none(*pmd); + pte_t *pte; + + if (pmd_none(*pmd))
This should also check if pmd is already huge. Same for pud ?
+ return 1; + + pte = (pte_t *)pmd_page_vaddr(*pmd); + pmd_clear(pmd); + free_page((unsigned long)pte); + + return 1; } #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Chintan -- Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project