arm64: hugetlb: partial revert of 66b3923a1a0f

Commit 66b3923a1a0f ("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 #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
index 82d607c3614ed8454d19f2da5d44a6cc914ee0b3..da30529bb1f65c9e3d5408b2e28ab31bc2283211 100644 (file)
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -306,10 +306,6 @@ 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;
@@ -317,13 +313,3 @@ static __init int setup_hugepagesz(char *opt)
        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