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Date: Tue, 7 May 2019 01:38:15 -0400 From: Sasha Levin <sashal@...nel.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Jan Kara <jack@...e.cz>, "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>, Dan Williams <dan.j.williams@...el.com>, Chandan Rajendra <chandan@...ux.ibm.com>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org>, Sasha Levin <alexander.levin@...rosoft.com>, linux-mm@...ck.org Subject: [PATCH AUTOSEL 4.14 86/95] mm/memory.c: fix modifying of page protection by insert_pfn() From: Jan Kara <jack@...e.cz> [ Upstream commit cae85cb8add35f678cf487139d05e083ce2f570a ] Aneesh has reported that PPC triggers the following warning when excercising DAX code: IP set_pte_at+0x3c/0x190 LR insert_pfn+0x208/0x280 Call Trace: insert_pfn+0x68/0x280 dax_iomap_pte_fault.isra.7+0x734/0xa40 __xfs_filemap_fault+0x280/0x2d0 do_wp_page+0x48c/0xa40 __handle_mm_fault+0x8d0/0x1fd0 handle_mm_fault+0x140/0x250 __do_page_fault+0x300/0xd60 handle_page_fault+0x18 Now that is WARN_ON in set_pte_at which is VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep)); The problem is that on some architectures set_pte_at() cannot cope with a situation where there is already some (different) valid entry present. Use ptep_set_access_flags() instead to modify the pfn which is built to deal with modifying existing PTE. Link: http://lkml.kernel.org/r/20190311084537.16029-1-jack@suse.cz Fixes: b2770da64254 "mm: add vm_insert_mixed_mkwrite()" Signed-off-by: Jan Kara <jack@...e.cz> Reported-by: "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@...ux.ibm.com> Acked-by: Dan Williams <dan.j.williams@...el.com> Cc: Chandan Rajendra <chandan@...ux.ibm.com> Cc: <stable@...r.kernel.org> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com> --- mm/memory.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index f99b64ca1303..e9bce27bc18c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1813,10 +1813,12 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, WARN_ON_ONCE(!is_zero_pfn(pte_pfn(*pte))); goto out_unlock; } - entry = *pte; - goto out_mkwrite; - } else - goto out_unlock; + entry = pte_mkyoung(*pte); + entry = maybe_mkwrite(pte_mkdirty(entry), vma); + if (ptep_set_access_flags(vma, addr, pte, entry, 1)) + update_mmu_cache(vma, addr, pte); + } + goto out_unlock; } /* Ok, finally just insert the thing.. */ @@ -1825,7 +1827,6 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, else entry = pte_mkspecial(pfn_t_pte(pfn, prot)); -out_mkwrite: if (mkwrite) { entry = pte_mkyoung(entry); entry = maybe_mkwrite(pte_mkdirty(entry), vma); -- 2.20.1
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