From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Ungerer Subject: Re: [PATCH] m68k: fix "bad page state" oops on ColdFire boot Date: Mon, 18 Jun 2018 23:59:40 +1000 Message-ID: <8cd9643d-0855-ac30-41cb-7de24314da00@linux-m68k.org> References: <20180618060426.24497-1-gerg@linux-m68k.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Geert Uytterhoeven Cc: Matthew Wilcox , Linux/m68k , Linux Kernel Mailing List List-Id: linux-m68k@vger.kernel.org Hi Geert, On 18/06/18 16:58, Geert Uytterhoeven wrote: > Hi Greg, > > On Mon, Jun 18, 2018 at 8:06 AM Greg Ungerer wrote: >> Booting a ColdFire m68k core with MMU enabled causes a "bad page state" >> oops since commit 1d40a5ea01d5 ("mm: mark pages in use for page tables"): >> >> BUG: Bad page state in process sh pfn:01ce2 >> page:004fefc8 count:0 mapcount:-1024 mapping:00000000 index:0x0 >> flags: 0x0() >> raw: 00000000 00000000 00000000 fffffbff 00000000 00000100 00000200 00000000 >> raw: 039c4000 >> page dumped because: nonzero mapcount >> Modules linked in: >> CPU: 0 PID: 22 Comm: sh Not tainted 4.17.0-07461-g1d40a5ea01d5 #13 >> >> Fix by calling pgtable_page_dtor() in our __pte_free_tlb() code path, >> so that the PG_table flag is cleared before we free the pte page. >> >> Signed-off-by: Greg Ungerer >> CC: Matthew Wilcox >> --- >> arch/m68k/include/asm/mcf_pgalloc.h | 1 + >> 1 file changed, 1 insertion(+) >> >> Matthew: I came across this thread at https://lkml.org/lkml/2018/6/17/163 >> about a similar problem with openrisc. Based on that I came up >> with this fix for m68k/ColdFire. Fixes the issue for me. >> >> diff --git a/arch/m68k/include/asm/mcf_pgalloc.h b/arch/m68k/include/asm/mcf_pgalloc.h >> index 8b707c249026..8c441eb57b80 100644 >> --- a/arch/m68k/include/asm/mcf_pgalloc.h >> +++ b/arch/m68k/include/asm/mcf_pgalloc.h >> @@ -44,6 +44,7 @@ extern inline pmd_t *pmd_alloc_kernel(pgd_t *pgd, unsigned long address) >> static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t page, >> unsigned long address) >> { >> + pgtable_page_dtor(page); >> __free_page(page); >> } > > Do you need a call to pgtable_page_dtor() in pte_free(), too? > On x86 (and motorola_pgalloc.h and sun3_pgalloc.h FWIW), both functions > call pgtable_page_dtor(). I am thinking yes, looking at those other examples. Regards Greg