| Message ID | 1544158388-20832-1-git-send-email-kernelfans@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [PATCHv2] mm/pageblock: throw compiling time error if pageblock_bits can not hold MIGRATE_TYPES | expand |
On 12/7/18 5:53 AM, Pingfan Liu wrote: > Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. > If someone adds extra migrate type, then he may forget to enlarge the > NR_PAGEBLOCK_BITS. Hence it requires some way to fix. > NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro > spread on two different .h file with reverse dependency, it is a little > hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to > remind such relation in compiling-time. > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Michal Hocko <mhocko@suse.com> > Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Oscar Salvador <osalvador@suse.de> > Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> > --- > include/linux/pageblock-flags.h | 5 +++-- > mm/page_alloc.c | 3 ++- > 2 files changed, 5 insertions(+), 3 deletions(-) > > diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h > index 9132c5c..fe0aec4 100644 > --- a/include/linux/pageblock-flags.h > +++ b/include/linux/pageblock-flags.h > @@ -25,11 +25,12 @@ > > #include <linux/types.h> > > +#define PB_migratetype_bits 3 > /* Bit indices that affect a whole block of pages */ > enum pageblock_bits { > PB_migrate, > - PB_migrate_end = PB_migrate + 3 - 1, > - /* 3 bits required for migrate types */ > + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, > + /* n bits required for migrate types */ > PB_migrate_skip,/* If set the block is skipped by compaction */ > > /* > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 2ec9cc4..1a22d8d 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -425,7 +425,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, > unsigned long bitidx, word_bitidx; > unsigned long old_word, word; > > - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); Why delete this one? It's for something a bit different and also still valid. > + BUILD_BUG_ON(order_base_2(MIGRATE_TYPES) > + != (PB_migratetype_bits - 1)); I think this should use the '>' operator. It's fine if there are less types than what can fit into 3 bits. AFAICS for !CONFIG_DMA and !CONFIG_MEMORY_ISOLATION there are just 4 types that fit into 2 bits... > > bitmap = get_pageblock_bitmap(page, pfn); > bitidx = pfn_to_bitidx(page, pfn); >
Hi Pingfan,
Thank you for the patch! Yet something to improve:
[auto build test ERROR on linus/master]
[also build test ERROR on v4.20-rc5 next-20181207]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Pingfan-Liu/mm-pageblock-throw-compiling-time-error-if-pageblock_bits-can-not-hold-MIGRATE_TYPES/20181207-161514
config: x86_64-randconfig-x017-201848 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
# save the attached .config to linux build tree
make ARCH=x86_64
All errors (new ones prefixed by >>):
In file included from include/asm-generic/bug.h:5:0,
from arch/x86/include/asm/bug.h:47,
from include/linux/bug.h:5,
from include/linux/mmdebug.h:5,
from include/linux/mm.h:9,
from mm/page_alloc.c:18:
mm/page_alloc.c: In function 'set_pfnblock_flags_mask':
>> include/linux/compiler.h:372:38: error: call to '__compiletime_assert_429' declared with attribute error: BUILD_BUG_ON failed: order_base_2(MIGRATE_TYPES) != (PB_migratetype_bits - 1)
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
^
include/linux/compiler.h:353:4: note: in definition of macro '__compiletime_assert'
prefix ## suffix(); \
^~~~~~
include/linux/compiler.h:372:2: note: in expansion of macro '_compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
^~~~~~~~~~~~~~~~~~~
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)
^~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:69:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
^~~~~~~~~~~~~~~~
mm/page_alloc.c:428:2: note: in expansion of macro 'BUILD_BUG_ON'
BUILD_BUG_ON(order_base_2(MIGRATE_TYPES)
^~~~~~~~~~~~
vim +/__compiletime_assert_429 +372 include/linux/compiler.h
9a8ab1c3 Daniel Santos 2013-02-21 358
9a8ab1c3 Daniel Santos 2013-02-21 359 #define _compiletime_assert(condition, msg, prefix, suffix) \
9a8ab1c3 Daniel Santos 2013-02-21 360 __compiletime_assert(condition, msg, prefix, suffix)
9a8ab1c3 Daniel Santos 2013-02-21 361
9a8ab1c3 Daniel Santos 2013-02-21 362 /**
9a8ab1c3 Daniel Santos 2013-02-21 363 * compiletime_assert - break build and emit msg if condition is false
9a8ab1c3 Daniel Santos 2013-02-21 364 * @condition: a compile-time constant condition to check
9a8ab1c3 Daniel Santos 2013-02-21 365 * @msg: a message to emit if condition is false
9a8ab1c3 Daniel Santos 2013-02-21 366 *
9a8ab1c3 Daniel Santos 2013-02-21 367 * In tradition of POSIX assert, this macro will break the build if the
9a8ab1c3 Daniel Santos 2013-02-21 368 * supplied condition is *false*, emitting the supplied error message if the
9a8ab1c3 Daniel Santos 2013-02-21 369 * compiler has support to do so.
9a8ab1c3 Daniel Santos 2013-02-21 370 */
9a8ab1c3 Daniel Santos 2013-02-21 371 #define compiletime_assert(condition, msg) \
9a8ab1c3 Daniel Santos 2013-02-21 @372 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
9a8ab1c3 Daniel Santos 2013-02-21 373
:::::: The code at line 372 was first introduced by commit
:::::: 9a8ab1c39970a4938a72d94e6fd13be88a797590 bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG
:::::: TO: Daniel Santos <daniel.santos@pobox.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
On Fri, Dec 7, 2018 at 3:36 PM Vlastimil Babka <vbabka@suse.cz> wrote: > > On 12/7/18 5:53 AM, Pingfan Liu wrote: > > Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. > > If someone adds extra migrate type, then he may forget to enlarge the > > NR_PAGEBLOCK_BITS. Hence it requires some way to fix. > > NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro > > spread on two different .h file with reverse dependency, it is a little > > hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to > > remind such relation in compiling-time. > > > > Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Michal Hocko <mhocko@suse.com> > > Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> > > Cc: Vlastimil Babka <vbabka@suse.cz> > > Cc: Oscar Salvador <osalvador@suse.de> > > Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> > > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > --- > > include/linux/pageblock-flags.h | 5 +++-- > > mm/page_alloc.c | 3 ++- > > 2 files changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h > > index 9132c5c..fe0aec4 100644 > > --- a/include/linux/pageblock-flags.h > > +++ b/include/linux/pageblock-flags.h > > @@ -25,11 +25,12 @@ > > > > #include <linux/types.h> > > > > +#define PB_migratetype_bits 3 > > /* Bit indices that affect a whole block of pages */ > > enum pageblock_bits { > > PB_migrate, > > - PB_migrate_end = PB_migrate + 3 - 1, > > - /* 3 bits required for migrate types */ > > + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, > > + /* n bits required for migrate types */ > > PB_migrate_skip,/* If set the block is skipped by compaction */ > > > > /* > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 2ec9cc4..1a22d8d 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -425,7 +425,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, > > unsigned long bitidx, word_bitidx; > > unsigned long old_word, word; > > > > - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); > > Why delete this one? It's for something a bit different and also still > valid. > I think it is dependent on PB_migratetype_bits (plus 1 dedicated bit for skip), hence the later one implies it. > > + BUILD_BUG_ON(order_base_2(MIGRATE_TYPES) > > + != (PB_migratetype_bits - 1)); > > I think this should use the '>' operator. It's fine if there are less If ">" is chosen, then it allows wasted bits. I had thought it is not the purpose of the design, hence disard the ">". Otherwise, what about using warning on ">"? > types than what can fit into 3 bits. AFAICS for !CONFIG_DMA and > !CONFIG_MEMORY_ISOLATION there are just 4 types that fit into 2 bits... > Oh, yes, you are right. How about this: #if defined(CONFIG_DMA) || defined(CONFIG_MEMORY_ISOLATION) #define PB_migratetype_bits 3 #else #define PB_migratetype_bits 2 #endif Thanks for your kindly review. Regards, Pingfan > > > > bitmap = get_pageblock_bitmap(page, pfn); > > bitidx = pfn_to_bitidx(page, pfn); > > >
On 12/10/18 4:15 AM, Pingfan Liu wrote: > On Fri, Dec 7, 2018 at 3:36 PM Vlastimil Babka <vbabka@suse.cz> wrote: >> >> On 12/7/18 5:53 AM, Pingfan Liu wrote: >>> Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. >>> If someone adds extra migrate type, then he may forget to enlarge the >>> NR_PAGEBLOCK_BITS. Hence it requires some way to fix. >>> NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro >>> spread on two different .h file with reverse dependency, it is a little >>> hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to >>> remind such relation in compiling-time. >>> >>> Signed-off-by: Pingfan Liu <kernelfans@gmail.com> >>> Cc: Andrew Morton <akpm@linux-foundation.org> >>> Cc: Michal Hocko <mhocko@suse.com> >>> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> >>> Cc: Vlastimil Babka <vbabka@suse.cz> >>> Cc: Oscar Salvador <osalvador@suse.de> >>> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> >>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> >>> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> >>> --- >>> include/linux/pageblock-flags.h | 5 +++-- >>> mm/page_alloc.c | 3 ++- >>> 2 files changed, 5 insertions(+), 3 deletions(-) >>> >>> diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h >>> index 9132c5c..fe0aec4 100644 >>> --- a/include/linux/pageblock-flags.h >>> +++ b/include/linux/pageblock-flags.h >>> @@ -25,11 +25,12 @@ >>> >>> #include <linux/types.h> >>> >>> +#define PB_migratetype_bits 3 >>> /* Bit indices that affect a whole block of pages */ >>> enum pageblock_bits { >>> PB_migrate, >>> - PB_migrate_end = PB_migrate + 3 - 1, >>> - /* 3 bits required for migrate types */ >>> + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, >>> + /* n bits required for migrate types */ >>> PB_migrate_skip,/* If set the block is skipped by compaction */ >>> >>> /* >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >>> index 2ec9cc4..1a22d8d 100644 >>> --- a/mm/page_alloc.c >>> +++ b/mm/page_alloc.c >>> @@ -425,7 +425,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, >>> unsigned long bitidx, word_bitidx; >>> unsigned long old_word, word; >>> >>> - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); >> >> Why delete this one? It's for something a bit different and also still >> valid. >> > > I think it is dependent on PB_migratetype_bits (plus 1 dedicated bit > for skip), hence the later one implies it. No, NR_PAGEBLOCK_BITS simply to be 4 (or other number that can divide the number of bits in a word with no remainder), or set_pfnblock_flags_mask() will not function correctly. >>> + BUILD_BUG_ON(order_base_2(MIGRATE_TYPES) >>> + != (PB_migratetype_bits - 1)); >> >> I think this should use the '>' operator. It's fine if there are less > > If ">" is chosen, then it allows wasted bits. I had thought it is not > the purpose of the design, hence disard the ">". We do allow wasted bits, because we need NR_PAGEBLOCK_BITS to be 4 in any case, as explained above. > Otherwise, what about > using warning on ">"? I think it would be needed. >> types than what can fit into 3 bits. AFAICS for !CONFIG_DMA and >> !CONFIG_MEMORY_ISOLATION there are just 4 types that fit into 2 bits... >> > Oh, yes, you are right. How about this: > #if defined(CONFIG_DMA) || defined(CONFIG_MEMORY_ISOLATION) > #define PB_migratetype_bits 3 > #else > #define PB_migratetype_bits 2 > #endif I think it's not necessary. Really, we need to have 4 NR_PAGEBLOCK_BITS with the current code, and this leaves us with 3 bits for migratetype. The only thing to check is whether migratetypes fit into these 3 bits, IMHO. > Thanks for your kindly review. > > Regards, > Pingfan >>> >>> bitmap = get_pageblock_bitmap(page, pfn); >>> bitidx = pfn_to_bitidx(page, pfn); >>> >>
On Mon, Dec 10, 2018 at 3:46 PM Vlastimil Babka <vbabka@suse.cz> wrote: > > On 12/10/18 4:15 AM, Pingfan Liu wrote: > > On Fri, Dec 7, 2018 at 3:36 PM Vlastimil Babka <vbabka@suse.cz> wrote: > >> > >> On 12/7/18 5:53 AM, Pingfan Liu wrote: > >>> Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. > >>> If someone adds extra migrate type, then he may forget to enlarge the > >>> NR_PAGEBLOCK_BITS. Hence it requires some way to fix. > >>> NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro > >>> spread on two different .h file with reverse dependency, it is a little > >>> hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to > >>> remind such relation in compiling-time. > >>> > >>> Signed-off-by: Pingfan Liu <kernelfans@gmail.com> > >>> Cc: Andrew Morton <akpm@linux-foundation.org> > >>> Cc: Michal Hocko <mhocko@suse.com> > >>> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> > >>> Cc: Vlastimil Babka <vbabka@suse.cz> > >>> Cc: Oscar Salvador <osalvador@suse.de> > >>> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> > >>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > >>> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> > >>> --- > >>> include/linux/pageblock-flags.h | 5 +++-- > >>> mm/page_alloc.c | 3 ++- > >>> 2 files changed, 5 insertions(+), 3 deletions(-) > >>> > >>> diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h > >>> index 9132c5c..fe0aec4 100644 > >>> --- a/include/linux/pageblock-flags.h > >>> +++ b/include/linux/pageblock-flags.h > >>> @@ -25,11 +25,12 @@ > >>> > >>> #include <linux/types.h> > >>> > >>> +#define PB_migratetype_bits 3 > >>> /* Bit indices that affect a whole block of pages */ > >>> enum pageblock_bits { > >>> PB_migrate, > >>> - PB_migrate_end = PB_migrate + 3 - 1, > >>> - /* 3 bits required for migrate types */ > >>> + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, > >>> + /* n bits required for migrate types */ > >>> PB_migrate_skip,/* If set the block is skipped by compaction */ > >>> > >>> /* > >>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >>> index 2ec9cc4..1a22d8d 100644 > >>> --- a/mm/page_alloc.c > >>> +++ b/mm/page_alloc.c > >>> @@ -425,7 +425,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, > >>> unsigned long bitidx, word_bitidx; > >>> unsigned long old_word, word; > >>> > >>> - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); > >> > >> Why delete this one? It's for something a bit different and also still > >> valid. > >> > > > > I think it is dependent on PB_migratetype_bits (plus 1 dedicated bit > > for skip), hence the later one implies it. > > No, NR_PAGEBLOCK_BITS simply to be 4 (or other number that can divide > the number of bits in a word with no remainder), or > set_pfnblock_flags_mask() will not function correctly. > Yes, you are right. It will break the atomic. > >>> + BUILD_BUG_ON(order_base_2(MIGRATE_TYPES) > >>> + != (PB_migratetype_bits - 1)); > >> > >> I think this should use the '>' operator. It's fine if there are less > > > > If ">" is chosen, then it allows wasted bits. I had thought it is not > > the purpose of the design, hence disard the ">". > > We do allow wasted bits, because we need NR_PAGEBLOCK_BITS to be 4 in > any case, as explained above. > Right! > > Otherwise, what about > > using warning on ">"? > > I think it would be needed. > OK. > >> types than what can fit into 3 bits. AFAICS for !CONFIG_DMA and > >> !CONFIG_MEMORY_ISOLATION there are just 4 types that fit into 2 bits... > >> > > Oh, yes, you are right. How about this: > > #if defined(CONFIG_DMA) || defined(CONFIG_MEMORY_ISOLATION) > > #define PB_migratetype_bits 3 > > #else > > #define PB_migratetype_bits 2 > > #endif > > I think it's not necessary. Really, we need to have 4 NR_PAGEBLOCK_BITS > with the current code, and this leaves us with 3 bits for migratetype. > The only thing to check is whether migratetypes fit into these 3 bits, IMHO. > OK. I will update v3. Thanks and regards, Pingfan
diff --git a/include/linux/pageblock-flags.h b/include/linux/pageblock-flags.h index 9132c5c..fe0aec4 100644 --- a/include/linux/pageblock-flags.h +++ b/include/linux/pageblock-flags.h @@ -25,11 +25,12 @@ #include <linux/types.h> +#define PB_migratetype_bits 3 /* Bit indices that affect a whole block of pages */ enum pageblock_bits { PB_migrate, - PB_migrate_end = PB_migrate + 3 - 1, - /* 3 bits required for migrate types */ + PB_migrate_end = PB_migrate + PB_migratetype_bits - 1, + /* n bits required for migrate types */ PB_migrate_skip,/* If set the block is skipped by compaction */ /* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 2ec9cc4..1a22d8d 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -425,7 +425,8 @@ void set_pfnblock_flags_mask(struct page *page, unsigned long flags, unsigned long bitidx, word_bitidx; unsigned long old_word, word; - BUILD_BUG_ON(NR_PAGEBLOCK_BITS != 4); + BUILD_BUG_ON(order_base_2(MIGRATE_TYPES) + != (PB_migratetype_bits - 1)); bitmap = get_pageblock_bitmap(page, pfn); bitidx = pfn_to_bitidx(page, pfn);
Currently, NR_PAGEBLOCK_BITS and MIGRATE_TYPES are not associated by code. If someone adds extra migrate type, then he may forget to enlarge the NR_PAGEBLOCK_BITS. Hence it requires some way to fix. NR_PAGEBLOCK_BITS depends on MIGRATE_TYPES, while these macro spread on two different .h file with reverse dependency, it is a little hard to refer to MIGRATE_TYPES in pageblock-flag.h. This patch tries to remind such relation in compiling-time. Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Oscar Salvador <osalvador@suse.de> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> --- include/linux/pageblock-flags.h | 5 +++-- mm/page_alloc.c | 3 ++- 2 files changed, 5 insertions(+), 3 deletions(-)