Commit 147b6ac5 authored Sep 05, 2018 by Mark Rutland Committed by Sudarshan Rajagopalan Nov 05, 2018

arm64: fix erroneous warnings in page freeing functions



In pmd_free_pte_page() and pud_free_pmd_page() we try to warn if they
hit a present non-table entry. In both cases we'll warn for non-present
entries, as the VM_WARN_ON() only checks the entry is not a table entry.

This has been observed to result in warnings when booting a v4.19-rc2
kernel under qemu.

Fix this by bailing out earlier for non-present entries.

Change-Id: I53de930955be4cad557bd82ba1ec9581164964ec
Fixes: ec28bb9c9b0826d7 ("arm64: Implement page table free interfaces")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Git-Commit: fac880c7d074fdfca874114b5c47b36aa034e4ee
Git-Repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>

parent c8e910d7

arch/arm64/mm/mmu.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -1406,8 +1406,9 @@ int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)

		pmd = READ_ONCE(*pmdp);

		/* No-op for empty entry and WARN_ON for valid entry */
		if (!pmd_present(pmd) \|\| !pmd_table(pmd)) {
		if (!pmd_present(pmd))
		return 1;
		if (!pmd_table(pmd)) {
		VM_WARN_ON(!pmd_table(pmd));
		return 1;
		}
		@@ -1428,8 +1429,9 @@ int pud_free_pmd_page(pud_t *pudp, unsigned long addr)

		pud = READ_ONCE(*pudp);

		/* No-op for empty entry and WARN_ON for valid entry */
		if (!pud_present(pud) \|\| !pud_table(pud)) {
		if (!pud_present(pud))
		return 1;
		if (!pud_table(pud)) {
		VM_WARN_ON(!pud_table(pud));
		return 1;
		}