arm64: hugetlb: partial revert of 66b3923

wildea01 · wildea01 · commit ff7925848b50 · 2016-03-09T15:29:29.000Z
Commit 66b3923 ("arm64: hugetlb: add support for PTE contiguous bit") introduced support for huge pages using the contiguous bit in the PTE as opposed to block mappings, which may be slightly unwieldy (512M) in 64k page configurations. Unfortunately, this support has resulted in some late regressions when running the libhugetlbfs test suite with 64k pages and CONFIG_DEBUG_VM as a result of a BUG: | readback (2M: 64): ------------[ cut here ]------------ | kernel BUG at fs/hugetlbfs/inode.c:446! | Internal error: Oops - BUG: 0 [#1] SMP | Modules linked in: | CPU: 7 PID: 1448 Comm: readback Not tainted 4.5.0-rc7 torvalds#148 | Hardware name: linux,dummy-virt (DT) | task: fffffe0040964b00 ti: fffffe00c2668000 task.ti: fffffe00c2668000 | PC is at remove_inode_hugepages+0x44c/0x480 | LR is at remove_inode_hugepages+0x264/0x480 Rather than revert the entire patch, simply avoid advertising the contiguous huge page sizes for now while people are actively working on a fix. This patch can then be reverted once things have been sorted out. Cc: David Woods <dwoods@ezchip.com> Reported-by: Steve Capper <steve.capper@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
@@ -306,24 +306,10 @@ static __init int setup_hugepagesz(char *opt)
 		hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
 	} else if (ps == PUD_SIZE) {
 		hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
-	} else if (ps == (PAGE_SIZE * CONT_PTES)) {
-		hugetlb_add_hstate(CONT_PTE_SHIFT);
-	} else if (ps == (PMD_SIZE * CONT_PMDS)) {
-		hugetlb_add_hstate((PMD_SHIFT + CONT_PMD_SHIFT) - PAGE_SHIFT);
 	} else {
 		pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10);
 		return 0;
 	}
 	return 1;
 }
 __setup("hugepagesz=", setup_hugepagesz);
-
-#ifdef CONFIG_ARM64_64K_PAGES
-static __init int add_default_hugepagesz(void)
-{
-	if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL)
-		hugetlb_add_hstate(CONT_PMD_SHIFT);
-	return 0;
-}
-arch_initcall(add_default_hugepagesz);
-#endif
