Re: mmotm 2021-08-05-19-46 uploaded (mm/filemap.c)
From: SeongJae Park <hidden>
Date: 2021-08-06 09:22:58
Also in:
linux-fsdevel, linux-mm, lkml, mm-commits
Subsystem:
damon, memory management, the rest · Maintainers:
SJ Park, Andrew Morton, Linus Torvalds
From: SeongJae Park <redacted> Hello Randy, On Thu, 5 Aug 2021 22:00:11 -0700 Randy Dunlap [off-list ref] wrote: [...]
on i386, I am seeing lots of build errors due to references to
some PAGE_ flags that are only defined for 64BIT:
In file included from ../mm/filemap.c:44:0:
../include/linux/page_idle.h: In function ‘folio_test_young’:
../include/linux/page_idle.h:25:18: error: ‘PAGE_EXT_YOUNG’ undeclared (first use in this function); did you mean ‘PAGEOUTRUN’?
return test_bit(PAGE_EXT_YOUNG, &page_ext->flags);
^~~~~~~~~~~~~~
PAGEOUTRUN[...]
quoted hunk ↗ jump to hunk
See:--- a/include/linux/page_ext.h~mm-idle_page_tracking-make-pg_idle-reusable +++ a/include/linux/page_ext.h@@ -19,7 +19,7 @@ struct page_ext_operations { enum page_ext_flags { PAGE_EXT_OWNER, PAGE_EXT_OWNER_ALLOCATED, -#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT) +#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT) PAGE_EXT_YOUNG, PAGE_EXT_IDLE, #endif
Thanks for this report! However, the flag is not defined for only-64BIT but
none-64BIT.
'enum page_ext_flags' is defined when 'CONFIG_PAGE_EXTENSION' is set. It is
automatically set for non-64BIT when 'CONFIG_IDLE_PAGE_TRACKING' or
'CONFIG_DAMON_VADDR' is set. However, 'CONFIG_PAGE_IDLE_FLAG' doesn't. So, if
'CONFIG_PAGE_IDLE_FLAG' is set but 'CONFIG_PAGE_EXTENSION' is not, this issue
can be reproduced.
I was able to reproduce this issue with:
make ARCH=i386 allnoconfig
echo 'CONFIG_PAGE_IDLE_FLAG=y' >> .config
make olddefconfig
make ARCH=i386
And, confirmed below change fixes it.
--- a/mm/Kconfig
+++ b/mm/Kconfig@@ -741,6 +741,7 @@ config DEFERRED_STRUCT_PAGE_INIT config PAGE_IDLE_FLAG bool "Add PG_idle and PG_young flags" + select PAGE_EXTENSION if !64BIT help This feature adds PG_idle and PG_young flags in 'struct page'. PTE Accessed bit writers can set the state of the bit in the flags to let
Also, below change would make more sense:
@@ -749,7 +750,6 @@ config PAGE_IDLE_FLAG config IDLE_PAGE_TRACKING bool "Enable idle page tracking" depends on SYSFS && MMU && BROKEN - select PAGE_EXTENSION if !64BIT select PAGE_IDLE_FLAG help This feature allows to estimate the amount of user pages that have
diff --git a/mm/damon/Kconfig b/mm/damon/Kconfig
index 455995152697..37024798a97c 100644
--- a/mm/damon/Kconfig
+++ b/mm/damon/Kconfig@@ -27,7 +27,6 @@ config DAMON_KUNIT_TEST config DAMON_VADDR bool "Data access monitoring primitives for virtual address spaces" depends on DAMON && MMU - select PAGE_EXTENSION if !64BIT select PAGE_IDLE_FLAG help This builds the default data access monitoring primitives for DAMON
I will format these as patches and post soon. Thanks, SeongJae Park
-- ~Randy Reported-by: Randy Dunlap <redacted>