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Message-Id: <1d6c1ea9-6488-5e25-68b7-6f4aa07d1945@linux.vnet.ibm.com>
Date: Mon, 5 Mar 2018 11:50:21 +0100
From: Laurent Dufour <ldufour@...ux.vnet.ibm.com>
To: Daniel Jordan <daniel.m.jordan@...cle.com>,
paulmck@...ux.vnet.ibm.com, peterz@...radead.org,
akpm@...ux-foundation.org, kirill@...temov.name,
ak@...ux.intel.com, mhocko@...nel.org, dave@...olabs.net,
jack@...e.cz, Matthew Wilcox <willy@...radead.org>,
benh@...nel.crashing.org, mpe@...erman.id.au, paulus@...ba.org,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, hpa@...or.com,
Will Deacon <will.deacon@....com>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Andrea Arcangeli <aarcange@...hat.com>,
Alexei Starovoitov <alexei.starovoitov@...il.com>,
kemi.wang@...el.com, sergey.senozhatsky.work@...il.com
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
haren@...ux.vnet.ibm.com, khandual@...ux.vnet.ibm.com,
npiggin@...il.com, bsingharora@...il.com,
Tim Chen <tim.c.chen@...ux.intel.com>,
linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v8 18/24] mm: Provide speculative fault infrastructure
Hi Jordan,
Thanks for reporting this.
On 26/02/2018 18:16, Daniel Jordan wrote:
> Hi Laurent,
>
> This series doesn't build for me[*] when CONFIG_TRANSPARENT_HUGEPAGE is unset.
>
> The problem seems to be that the BUILD_BUG() version of pmd_same is called in
> pte_map_lock:
>
> On 02/16/2018 10:25 AM, Laurent Dufour wrote:
>> +static bool pte_map_lock(struct vm_fault *vmf)
>> +{
> ...snip...
>> + if (!pmd_same(pmdval, vmf->orig_pmd))
>> + goto out;
>
> Since SPF can now call pmd_same without THP, maybe the way to fix it is just
>
> diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
> index 2cfa3075d148..e130692db24a 100644
> --- a/include/asm-generic/pgtable.h
> +++ b/include/asm-generic/pgtable.h
> @@ -375,7 +375,8 @@ static inline int pte_unused(pte_t pte)
> #endif
>
> #ifndef __HAVE_ARCH_PMD_SAME
> -#ifdef CONFIG_TRANSPARENT_HUGEPAGE
> +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || \
> + defined(CONFIG_SPECULATIVE_PAGE_FAULT)
> static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
> {
> return pmd_val(pmd_a) == pmd_val(pmd_b);
We can't fix that this way because some architectures define their own
pmd_same() function (like ppc64), thus forcing the define here will be useless
since __HAVE_ARCH_PMD_SAME is set in that case.
The right way to fix that is to _not check_ for the PMD value in pte_spinlock()
when CONFIG_TRANSPARENT_HUGEPAGE is not set since there is no risk of
collapsing operation in our back if THP are disabled.
I'll fix that in the next version.
Laurent.
> ?
>
> Daniel
>
>
> [*] The errors are:
>
> In file included from /home/dmjordan/src/linux/include/linux/kernel.h:10:0,
> from /home/dmjordan/src/linux/include/linux/list.h:9,
> from /home/dmjordan/src/linux/include/linux/smp.h:12,
> from /home/dmjordan/src/linux/include/linux/kernel_stat.h:5,
> from /home/dmjordan/src/linux/mm/memory.c:41:
> In function ‘pmd_same.isra.104’,
> inlined from ‘pte_map_lock’ at /home/dmjordan/src/linux/mm/memory.c:2380:7:
> /home/dmjordan/src/linux/include/linux/compiler.h:324:38: error: call to
> ‘__compiletime_assert_391’ declared with attribute error: BUILD_BUG failed
> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
> ^
> /home/dmjordan/src/linux/include/linux/compiler.h:304:4: note: in definition of
> macro ‘__compiletime_assert’
> prefix ## suffix(); \
> ^~~~~~
> /home/dmjordan/src/linux/include/linux/compiler.h:324:2: note: in expansion of
> macro ‘_compiletime_assert’
> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
> ^~~~~~~~~~~~~~~~~~~
> /home/dmjordan/src/linux/include/linux/build_bug.h:45:37: note: in expansion of
> macro ‘compiletime_assert’
> #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> ^~~~~~~~~~~~~~~~~~
> /home/dmjordan/src/linux/include/linux/build_bug.h:79:21: note: in expansion of
> macro ‘BUILD_BUG_ON_MSG’
> #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
> ^~~~~~~~~~~~~~~~
> /home/dmjordan/src/linux/include/asm-generic/pgtable.h:391:2: note: in
> expansion of macro ‘BUILD_BUG’
> BUILD_BUG();
> ^~~~~~~~~
> CC block/elevator.o
> CC crypto/crypto_wq.o
> In function ‘pmd_same.isra.104’,
> inlined from ‘pte_spinlock’ at /home/dmjordan/src/linux/mm/memory.c:2326:7,
> inlined from ‘handle_pte_fault’ at
> /home/dmjordan/src/linux/mm/memory.c:4181:7:
> /home/dmjordan/src/linux/include/linux/compiler.h:324:38: error: call to
> ‘__compiletime_assert_391’ declared with attribute error: BUILD_BUG failed
> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
> ^
> /home/dmjordan/src/linux/include/linux/compiler.h:304:4: note: in definition of
> macro ‘__compiletime_assert’
> prefix ## suffix(); \
> ^~~~~~
> /home/dmjordan/src/linux/include/linux/compiler.h:324:2: note: in expansion of
> macro ‘_compiletime_assert’
> _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
> ^~~~~~~~~~~~~~~~~~~
> /home/dmjordan/src/linux/include/linux/build_bug.h:45:37: note: in expansion of
> macro ‘compiletime_assert’
> #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
> ^~~~~~~~~~~~~~~~~~
> /home/dmjordan/src/linux/include/linux/build_bug.h:79:21: note: in expansion of
> macro ‘BUILD_BUG_ON_MSG’
> #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
> ^~~~~~~~~~~~~~~~
> /home/dmjordan/src/linux/include/asm-generic/pgtable.h:391:2: note: in
> expansion of macro ‘BUILD_BUG’
> BUILD_BUG();
> ^~~~~~~~~
> ...
> make[2]: *** [/home/dmjordan/src/linux/scripts/Makefile.build:316: mm/memory.o]
> Error 1
> make[1]: *** [/home/dmjordan/src/linux/Makefile:1047: mm] Error 2
>
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