diff mbox series

[v3,4/6] mm: pvmw: add support for walking devmap pages

Message ID 20220228063536.24911-5-songmuchun@bytedance.com (mailing list archive)
State New, archived
Headers show
Series Fix some bugs related to ramp and dax | expand

Commit Message

Muchun Song Feb. 28, 2022, 6:35 a.m. UTC
The devmap pages can not use page_vma_mapped_walk() to check if a huge
devmap page is mapped into a vma.  Add support for walking huge devmap
pages so that DAX can use it in the next patch.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/page_vma_mapped.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

kernel test robot Feb. 28, 2022, 5:35 p.m. UTC | #1
Hi Muchun,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on hnaz-mm/master]
[also build test ERROR on next-20220225]
[cannot apply to linus/master v5.17-rc6]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Muchun-Song/Fix-some-bugs-related-to-ramp-and-dax/20220228-143753
base:   https://github.com/hnaz/linux-mm master
config: riscv-randconfig-r012-20220227 (https://download.01.org/0day-ci/archive/20220228/202202281913.ZakSkynK-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # https://github.com/0day-ci/linux/commit/4b08af172f30c61ae5f43ec23642e2767371247e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Muchun-Song/Fix-some-bugs-related-to-ramp-and-dax/20220228-143753
        git checkout 4b08af172f30c61ae5f43ec23642e2767371247e
        # save the config file to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

>> mm/page_vma_mapped.c:113:13: error: call to __compiletime_assert_258 declared with 'error' attribute: BUILD_BUG failed
           if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn)
                      ^
   include/linux/huge_mm.h:105:26: note: expanded from macro 'HPAGE_PMD_NR'
   #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
                            ^
   include/linux/huge_mm.h:104:26: note: expanded from macro 'HPAGE_PMD_ORDER'
   #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
                            ^
   include/linux/huge_mm.h:307:28: note: expanded from macro 'HPAGE_PMD_SHIFT'
   #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
                              ^
   note: (skipping 3 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
   include/linux/compiler_types.h:335:2: note: expanded from macro '_compiletime_assert'
           __compiletime_assert(condition, msg, prefix, suffix)
           ^
   include/linux/compiler_types.h:328:4: note: expanded from macro '__compiletime_assert'
                           prefix ## suffix();                             \
                           ^
   <scratch space>:73:1: note: expanded from here
   __compiletime_assert_258
   ^
   1 error generated.


vim +/error +113 mm/page_vma_mapped.c

9188af981d385d Andrew Morton      2022-02-25  109  
9188af981d385d Andrew Morton      2022-02-25  110  /* Returns true if the two ranges overlap.  Careful to not overflow. */
9188af981d385d Andrew Morton      2022-02-25  111  static bool check_pmd(unsigned long pfn, struct page_vma_mapped_walk *pvmw)
9188af981d385d Andrew Morton      2022-02-25  112  {
9188af981d385d Andrew Morton      2022-02-25 @113  	if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn)
9188af981d385d Andrew Morton      2022-02-25  114  		return false;
9188af981d385d Andrew Morton      2022-02-25  115  	if (pfn > pvmw->pfn + pvmw->nr_pages - 1)
9188af981d385d Andrew Morton      2022-02-25  116  		return false;
9188af981d385d Andrew Morton      2022-02-25  117  	return true;
ace71a19cec5eb Kirill A. Shutemov 2017-02-24  118  }
ace71a19cec5eb Kirill A. Shutemov 2017-02-24  119  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Andrew Morton Feb. 28, 2022, 9:26 p.m. UTC | #2
On Mon, 28 Feb 2022 14:35:34 +0800 Muchun Song <songmuchun@bytedance.com> wrote:

> The devmap pages can not use page_vma_mapped_walk() to check if a huge
> devmap page is mapped into a vma.  Add support for walking huge devmap
> pages so that DAX can use it in the next patch.
> 

x86_64 allnoconfig:

In file included from <command-line>:
In function 'check_pmd',
    inlined from 'page_vma_mapped_walk' at mm/page_vma_mapped.c:219:10:
././include/linux/compiler_types.h:347:45: error: call to '__compiletime_assert_232' declared with attribute error: BUILD_BUG failed
  347 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
      |                                             ^
././include/linux/compiler_types.h:328:25: note: in definition of macro '__compiletime_assert'
  328 |                         prefix ## suffix();                             \
      |                         ^~~~~~
././include/linux/compiler_types.h:347:9: note: in expansion of macro '_compiletime_assert'
  347 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
      |         ^~~~~~~~~~~~~~~~~~~
./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
   39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
      |                                     ^~~~~~~~~~~~~~~~~~
./include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG'
   59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
      |                     ^~~~~~~~~~~~~~~~
./include/linux/huge_mm.h:307:28: note: in expansion of macro 'BUILD_BUG'
  307 | #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
      |                            ^~~~~~~~~
./include/linux/huge_mm.h:104:26: note: in expansion of macro 'HPAGE_PMD_SHIFT'
  104 | #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
      |                          ^~~~~~~~~~~~~~~
./include/linux/huge_mm.h:105:26: note: in expansion of macro 'HPAGE_PMD_ORDER'
  105 | #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
      |                          ^~~~~~~~~~~~~~~
mm/page_vma_mapped.c:113:20: note: in expansion of macro 'HPAGE_PMD_NR'
  113 |         if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn)
      |                    ^~~~~~~~~~~~
make[1]: *** [scripts/Makefile.build:288: mm/page_vma_mapped.o] Error 1
make: *** [Makefile:1971: mm] Error 2


because check_pmd() uses HPAGE_PMD_NR and

#else /* CONFIG_TRANSPARENT_HUGEPAGE */
#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })

I don't immediately see why this patch triggers it...
Muchun Song March 1, 2022, 3:14 a.m. UTC | #3
On Tue, Mar 1, 2022 at 5:26 AM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Mon, 28 Feb 2022 14:35:34 +0800 Muchun Song <songmuchun@bytedance.com> wrote:
>
> > The devmap pages can not use page_vma_mapped_walk() to check if a huge
> > devmap page is mapped into a vma.  Add support for walking huge devmap
> > pages so that DAX can use it in the next patch.
> >
>
> x86_64 allnoconfig:
>
> In file included from <command-line>:
> In function 'check_pmd',
>     inlined from 'page_vma_mapped_walk' at mm/page_vma_mapped.c:219:10:
> ././include/linux/compiler_types.h:347:45: error: call to '__compiletime_assert_232' declared with attribute error: BUILD_BUG failed
>   347 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>       |                                             ^
> ././include/linux/compiler_types.h:328:25: note: in definition of macro '__compiletime_assert'
>   328 |                         prefix ## suffix();                             \
>       |                         ^~~~~~
> ././include/linux/compiler_types.h:347:9: note: in expansion of macro '_compiletime_assert'
>   347 |         _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
>       |         ^~~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert'
>    39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>       |                                     ^~~~~~~~~~~~~~~~~~
> ./include/linux/build_bug.h:59:21: note: in expansion of macro 'BUILD_BUG_ON_MSG'
>    59 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
>       |                     ^~~~~~~~~~~~~~~~
> ./include/linux/huge_mm.h:307:28: note: in expansion of macro 'BUILD_BUG'
>   307 | #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
>       |                            ^~~~~~~~~
> ./include/linux/huge_mm.h:104:26: note: in expansion of macro 'HPAGE_PMD_SHIFT'
>   104 | #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
>       |                          ^~~~~~~~~~~~~~~
> ./include/linux/huge_mm.h:105:26: note: in expansion of macro 'HPAGE_PMD_ORDER'
>   105 | #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
>       |                          ^~~~~~~~~~~~~~~
> mm/page_vma_mapped.c:113:20: note: in expansion of macro 'HPAGE_PMD_NR'
>   113 |         if ((pfn + HPAGE_PMD_NR - 1) < pvmw->pfn)
>       |                    ^~~~~~~~~~~~
> make[1]: *** [scripts/Makefile.build:288: mm/page_vma_mapped.o] Error 1
> make: *** [Makefile:1971: mm] Error 2
>
>
> because check_pmd() uses HPAGE_PMD_NR and
>
> #else /* CONFIG_TRANSPARENT_HUGEPAGE */
> #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
>
> I don't immediately see why this patch triggers it...

Maybe the reason is as follows.

The first check_pmd() is wrapped inside `if (pmd_trans_huge(pmde))`
block, since pmd_trans_huge() just returns 0, check_pmd() will be
optimized out.  There is a `if (!thp_migration_supported()) return;` block
before the second check_pmd(), however, thp_migration_supported()
returns 0 on riscv. So the second check_pmd() can be optimized out as
well.  I think I should replace `pmd_leaf` with `pmd_trans_huge() ||
pmd_devmap()`
to fix it.

Thanks.
diff mbox series

Patch

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 1187f9c1ec5b..3f337e4e7f5f 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -210,10 +210,10 @@  bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 		 */
 		pmde = READ_ONCE(*pvmw->pmd);
 
-		if (pmd_trans_huge(pmde) || is_pmd_migration_entry(pmde)) {
+		if (pmd_leaf(pmde) || is_pmd_migration_entry(pmde)) {
 			pvmw->ptl = pmd_lock(mm, pvmw->pmd);
 			pmde = *pvmw->pmd;
-			if (likely(pmd_trans_huge(pmde))) {
+			if (likely(pmd_leaf(pmde))) {
 				if (pvmw->flags & PVMW_MIGRATION)
 					return not_found(pvmw);
 				if (!check_pmd(pmd_pfn(pmde), pvmw))