From: Toshi Kani <toshi.kani@hpe.com>
To: mhocko@suse.com, akpm@linux-foundation.org, tglx@linutronix.de,
mingo@redhat.com, hpa@zytor.com
Cc: cpandya@codeaurora.org, linux-mm@kvack.org, x86@kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Toshi Kani <toshi.kani@hpe.com>,
Joerg Roedel <joro@8bytes.org>,
stable@vger.kernel.org
Subject: [PATCH v4 1/3] x86/mm: disable ioremap free page handling on x86-PAE
Date: Wed, 27 Jun 2018 08:13:46 -0600 [thread overview]
Message-ID: <20180627141348.21777-2-toshi.kani@hpe.com> (raw)
In-Reply-To: <20180627141348.21777-1-toshi.kani@hpe.com>
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(+)
diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c
index 47b5951e592b..1aeb7a5dbce5 100644
--- a/arch/x86/mm/pgtable.c
+++ b/arch/x86/mm/pgtable.c
@@ -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 */
#endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */
next prev parent reply other threads:[~2018-06-27 14:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-27 14:13 [PATCH v4 0/3] fix free pmd/pte page handlings on x86 Toshi Kani
2018-06-27 14:13 ` Toshi Kani [this message]
2018-07-04 19:39 ` [tip:x86/mm] x86/mm: Disable ioremap free page handling on x86-PAE tip-bot for Toshi Kani
2018-06-27 14:13 ` [PATCH v4 2/3] ioremap: Update pgtable free interfaces with addr Toshi Kani
2018-06-27 15:56 ` Will Deacon
2018-06-27 16:13 ` Kani, Toshi
2018-06-29 12:23 ` Will Deacon
2018-06-29 16:01 ` Kani, Toshi
2018-07-03 21:02 ` Thomas Gleixner
2018-07-04 17:36 ` Will Deacon
2018-07-04 19:39 ` Thomas Gleixner
2018-07-05 17:16 ` Will Deacon
2018-07-04 19:40 ` [tip:x86/mm] " tip-bot for Chintan Pandya
2018-06-27 14:13 ` [PATCH v4 3/3] x86/mm: add TLB purge to free pmd/pte page interfaces Toshi Kani
2018-07-04 19:40 ` [tip:x86/mm] x86/mm: Add " tip-bot for Toshi Kani
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