Re: [kbuild-all] Re: [PATCH v2] mm: page_alloc: dump migrate-failed pages

[Minchan Kim]

On Tue, Mar 09, 2021 at 08:41:44AM +0800, Rong Chen wrote:
> 
> 
> On 3/9/21 6:29 AM, Minchan Kim wrote:
> > On Tue, Mar 09, 2021 at 05:29:30AM +0800, kernel test robot wrote:
> > > Hi Minchan,
> > > 
> > > I love your patch! Perhaps something to improve:
> > > 
> > > [auto build test WARNING on hnaz-linux-mm/master]
> > > 
> > > url:    https://github.com/0day-ci/linux/commits/Minchan-Kim/mm-page_alloc-dump-migrate-failed-pages/20210309-042205
> > > base:   https://github.com/hnaz/linux-mm master
> > > config: m68k-allmodconfig (attached as .config)
> > > compiler: m68k-linux-gcc (GCC) 9.3.0
> > > 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
> > >          # https://github.com/0day-ci/linux/commit/3c635af37b862e9c601ee8d5818f7da9cd3e2e57
> > >          git remote add linux-review https://github.com/0day-ci/linux
> > >          git fetch --no-tags linux-review Minchan-Kim/mm-page_alloc-dump-migrate-failed-pages/20210309-042205
> > >          git checkout 3c635af37b862e9c601ee8d5818f7da9cd3e2e57
> > >          # save the attached .config to linux build tree
> > >          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k
> > > 
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > > 
> > > All warnings (new ones prefixed by >>):
> > > 
> > >     arch/m68k/include/asm/page_mm.h:169:49: warning: ordered comparison of pointer with null pointer [-Wextra]
> > >       169 | #define virt_addr_valid(kaddr) ((void *)(kaddr) >= (void *)PAGE_OFFSET && (void *)(kaddr) < high_memory)
> > >           |                                                 ^~
> > >     include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
> > >        78 | # define unlikely(x) __builtin_expect(!!(x), 0)
> > >           |                                          ^
> > >     include/linux/scatterlist.h:143:2: note: in expansion of macro 'BUG_ON'
> > >       143 |  BUG_ON(!virt_addr_valid(buf));
> > >           |  ^~~~~~
> > >     include/linux/scatterlist.h:143:10: note: in expansion of macro 'virt_addr_valid'
> > >       143 |  BUG_ON(!virt_addr_valid(buf));
> > >           |          ^~~~~~~~~~~~~~~
> > >     In file included from arch/m68k/include/asm/page.h:60,
> > >                      from arch/m68k/include/asm/thread_info.h:6,
> > >                      from include/linux/thread_info.h:38,
> > >                      from include/asm-generic/preempt.h:5,
> > >                      from ./arch/m68k/include/generated/asm/preempt.h:1,
> > >                      from include/linux/preempt.h:78,
> > >                      from include/linux/spinlock.h:51,
> > >                      from include/linux/mmzone.h:8,
> > >                      from include/linux/gfp.h:6,
> > >                      from include/linux/mm.h:10,
> > >                      from mm/page_alloc.c:19:
> > I am not sure this is triggered by the patch since I could see the
> > warn with reverting the patch.
> 
> Hi Minchan,
> 
> Only the lines prefixed by ">>" are related with the patch:
> 
> > > mm/page_alloc.c:8348:5: warning: no previous prototype for 'alloc_contig_ratelimit' [-Wmissing-prototypes]
> 
>     8348 | int alloc_contig_ratelimit(void)
>          |     ^~~~~~~~~~~~~~~~~~~~~~
> 
> > > mm/page_alloc.c:8353:6: warning: no previous prototype for 'dump_migrate_failure_pages' [-Wmissing-prototypes]
> 
>     8353 | void dump_migrate_failure_pages(struct list_head *page_list)
> 

Thanks for the clarification.

Then, below should fix the warning.
I will respin it at next revision once I get more feedback.

+#if defined(CONFIG_DYNAMIC_DEBUG) || \
+       (defined(CONFIG_DYNAMIC_DEBUG_CORE) && defined(DYNAMIC_DEBUG_MODULE))
+static void dump_migrate_failure_pages(struct list_head *page_list)
+{
+       static DEFINE_RATELIMIT_STATE(_rs,
+                                       DEFAULT_RATELIMIT_INTERVAL,
+                                       DEFAULT_RATELIMIT_BURST);
+
+       DEFINE_DYNAMIC_DEBUG_METADATA(descriptor,
+                       "migrate failure");
+       if (DYNAMIC_DEBUG_BRANCH(descriptor) && __ratelimit(&_rs)) {
+               struct page *page;
+
+               WARN(1, "failed callstack");
+               list_for_each_entry(page, page_list, lru)
+                       dump_page(page, "migration failure");
+       }
+}
+#else
+static inline void dump_migrate_failure_pages(struct list_head *page_list)
+{
+}
+#endif
+
 /* [start, end) must belong to a single zone. */
 static int __alloc_contig_migrate_range(struct compact_control *cc,
                                        unsigned long start, unsigned long end)
@@ -8496,6 +8520,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
                                NULL, (unsigned long)&mtc, cc->mode, MR_CONTIG_RANGE);
        }
        if (ret < 0) {
+               dump_migrate_failure_pages(&cc->migratepages);
                putback_movable_pages(&cc->migratepages);
                return ret;
        }