| Message ID | 20230617070955.1751393-1-linmiaohe@huawei.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/mm_init.c: remove obsolete macro HASH_SMALL | expand |
On Sat, Jun 17, 2023 at 03:09:55PM +0800, Miaohe Lin wrote: > HASH_SMALL only works when parameter numentries is 0. But the sole caller > futex_init() never calls alloc_large_system_hash() with numentries set to > 0. Doesn't it? What happens when CONFIG_BASE_SMALL is set? > So HASH_SMALL is obsolete and remove it. > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > include/linux/memblock.h | 2 -- > kernel/futex/core.c | 3 +-- > mm/mm_init.c | 10 +--------- > 3 files changed, 2 insertions(+), 13 deletions(-) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index f71ff9f0ec81..346d80809517 100644 > --- a/include/linux/memblock.h > +++ b/include/linux/memblock.h > @@ -581,8 +581,6 @@ extern void *alloc_large_system_hash(const char *tablename, > unsigned long high_limit); > > #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ > -#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min > - * shift passed via *_hash_shift */ > #define HASH_ZERO 0x00000004 /* Zero allocated hash table */ > > /* Only NUMA needs hash distribution. 64bit NUMA architectures have > diff --git a/kernel/futex/core.c b/kernel/futex/core.c > index 514e4582b863..f10587d1d481 100644 > --- a/kernel/futex/core.c > +++ b/kernel/futex/core.c > @@ -1132,8 +1132,7 @@ static int __init futex_init(void) > #endif > > futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues), > - futex_hashsize, 0, > - futex_hashsize < 256 ? HASH_SMALL : 0, > + futex_hashsize, 0, 0, > &futex_shift, NULL, > futex_hashsize, futex_hashsize); > futex_hashsize = 1UL << futex_shift; > diff --git a/mm/mm_init.c b/mm/mm_init.c > index d393631599a7..fab3c4649d5b 100644 > --- a/mm/mm_init.c > +++ b/mm/mm_init.c > @@ -2492,15 +2492,7 @@ void *__init alloc_large_system_hash(const char *tablename, > else > numentries <<= (PAGE_SHIFT - scale); > > - /* Make sure we've got at least a 0-order allocation.. */ > - if (unlikely(flags & HASH_SMALL)) { > - /* Makes no sense without HASH_EARLY */ > - WARN_ON(!(flags & HASH_EARLY)); > - if (!(numentries >> *_hash_shift)) { > - numentries = 1UL << *_hash_shift; > - BUG_ON(!numentries); > - } > - } else if (unlikely((numentries * bucketsize) < PAGE_SIZE)) > + if (unlikely((numentries * bucketsize) < PAGE_SIZE)) > numentries = PAGE_SIZE / bucketsize; > } > numentries = roundup_pow_of_two(numentries); > -- > 2.27.0 >
On 2023/6/17 15:56, Mike Rapoport wrote: > On Sat, Jun 17, 2023 at 03:09:55PM +0800, Miaohe Lin wrote: >> HASH_SMALL only works when parameter numentries is 0. But the sole caller >> futex_init() never calls alloc_large_system_hash() with numentries set to >> 0. > Thanks for your quick review. > Doesn't it? > What happens when CONFIG_BASE_SMALL is set? When CONFIG_BASE_SMALL is set, futex_hashsize is set to 16 and alloc_large_system_hash() is called with numentries == 16 && flags == HASH_SMALL. But in the alloc_large_system_hash(), we have the below logic: alloc_large_system_hash() { if (!numentries) { /* numentries == 16 here, so this code block is skipped. */ ... if (unlikely(flags & HASH_SMALL)) { /* So as here. */ ... } ... } So HASH_SMALL is just unused. Or am I miss something? Thanks. > >> So HASH_SMALL is obsolete and remove it. > >> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> >> --- >> include/linux/memblock.h | 2 -- >> kernel/futex/core.c | 3 +-- >> mm/mm_init.c | 10 +--------- >> 3 files changed, 2 insertions(+), 13 deletions(-) >> >> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >> index f71ff9f0ec81..346d80809517 100644 >> --- a/include/linux/memblock.h >> +++ b/include/linux/memblock.h >> @@ -581,8 +581,6 @@ extern void *alloc_large_system_hash(const char *tablename, >> unsigned long high_limit); >> >> #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ >> -#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min >> - * shift passed via *_hash_shift */ >> #define HASH_ZERO 0x00000004 /* Zero allocated hash table */ >> >> /* Only NUMA needs hash distribution. 64bit NUMA architectures have >> diff --git a/kernel/futex/core.c b/kernel/futex/core.c >> index 514e4582b863..f10587d1d481 100644 >> --- a/kernel/futex/core.c >> +++ b/kernel/futex/core.c >> @@ -1132,8 +1132,7 @@ static int __init futex_init(void) >> #endif >> >> futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues), >> - futex_hashsize, 0, >> - futex_hashsize < 256 ? HASH_SMALL : 0, >> + futex_hashsize, 0, 0, >> &futex_shift, NULL, >> futex_hashsize, futex_hashsize); >> futex_hashsize = 1UL << futex_shift; >> diff --git a/mm/mm_init.c b/mm/mm_init.c >> index d393631599a7..fab3c4649d5b 100644 >> --- a/mm/mm_init.c >> +++ b/mm/mm_init.c >> @@ -2492,15 +2492,7 @@ void *__init alloc_large_system_hash(const char *tablename, >> else >> numentries <<= (PAGE_SHIFT - scale); >> >> - /* Make sure we've got at least a 0-order allocation.. */ >> - if (unlikely(flags & HASH_SMALL)) { >> - /* Makes no sense without HASH_EARLY */ >> - WARN_ON(!(flags & HASH_EARLY)); >> - if (!(numentries >> *_hash_shift)) { >> - numentries = 1UL << *_hash_shift; >> - BUG_ON(!numentries); >> - } >> - } else if (unlikely((numentries * bucketsize) < PAGE_SIZE)) >> + if (unlikely((numentries * bucketsize) < PAGE_SIZE)) >> numentries = PAGE_SIZE / bucketsize; >> } >> numentries = roundup_pow_of_two(numentries); >> -- >> 2.27.0 >> >
On Sat, Jun 17, 2023 at 04:39:44PM +0800, Miaohe Lin wrote: > On 2023/6/17 15:56, Mike Rapoport wrote: > > On Sat, Jun 17, 2023 at 03:09:55PM +0800, Miaohe Lin wrote: > >> HASH_SMALL only works when parameter numentries is 0. But the sole caller > >> futex_init() never calls alloc_large_system_hash() with numentries set to > >> 0. > > > > Thanks for your quick review. > > > Doesn't it? > > What happens when CONFIG_BASE_SMALL is set? > > When CONFIG_BASE_SMALL is set, futex_hashsize is set to 16 and alloc_large_system_hash() is called with > numentries == 16 && flags == HASH_SMALL. But in the alloc_large_system_hash(), we have the below logic: > > alloc_large_system_hash() > { > if (!numentries) { /* numentries == 16 here, so this code block is skipped. */ > ... > if (unlikely(flags & HASH_SMALL)) { /* So as here. */ > ... > } > ... > } > > So HASH_SMALL is just unused. Or am I miss something? You are right, I've missed that. > Thanks. > > > > >> So HASH_SMALL is obsolete and remove it. > > > >> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > >> --- > >> include/linux/memblock.h | 2 -- > >> kernel/futex/core.c | 3 +-- > >> mm/mm_init.c | 10 +--------- > >> 3 files changed, 2 insertions(+), 13 deletions(-) > >> > >> diff --git a/include/linux/memblock.h b/include/linux/memblock.h > >> index f71ff9f0ec81..346d80809517 100644 > >> --- a/include/linux/memblock.h > >> +++ b/include/linux/memblock.h > >> @@ -581,8 +581,6 @@ extern void *alloc_large_system_hash(const char *tablename, > >> unsigned long high_limit); > >> > >> #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ > >> -#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min > >> - * shift passed via *_hash_shift */ > >> #define HASH_ZERO 0x00000004 /* Zero allocated hash table */ Can you update HASH_ZERO to 0x2? > >> > >> /* Only NUMA needs hash distribution. 64bit NUMA architectures have > >> diff --git a/kernel/futex/core.c b/kernel/futex/core.c > >> index 514e4582b863..f10587d1d481 100644 > >> --- a/kernel/futex/core.c > >> +++ b/kernel/futex/core.c > >> @@ -1132,8 +1132,7 @@ static int __init futex_init(void) > >> #endif > >> > >> futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues), > >> - futex_hashsize, 0, > >> - futex_hashsize < 256 ? HASH_SMALL : 0, > >> + futex_hashsize, 0, 0, > >> &futex_shift, NULL, > >> futex_hashsize, futex_hashsize); > >> futex_hashsize = 1UL << futex_shift; > >> diff --git a/mm/mm_init.c b/mm/mm_init.c > >> index d393631599a7..fab3c4649d5b 100644 > >> --- a/mm/mm_init.c > >> +++ b/mm/mm_init.c > >> @@ -2492,15 +2492,7 @@ void *__init alloc_large_system_hash(const char *tablename, > >> else > >> numentries <<= (PAGE_SHIFT - scale); > >> > >> - /* Make sure we've got at least a 0-order allocation.. */ > >> - if (unlikely(flags & HASH_SMALL)) { > >> - /* Makes no sense without HASH_EARLY */ > >> - WARN_ON(!(flags & HASH_EARLY)); > >> - if (!(numentries >> *_hash_shift)) { > >> - numentries = 1UL << *_hash_shift; > >> - BUG_ON(!numentries); > >> - } > >> - } else if (unlikely((numentries * bucketsize) < PAGE_SIZE)) > >> + if (unlikely((numentries * bucketsize) < PAGE_SIZE)) > >> numentries = PAGE_SIZE / bucketsize; > >> } > >> numentries = roundup_pow_of_two(numentries); > >> -- > >> 2.27.0 > >> > > >
On 2023/6/17 18:51, Mike Rapoport wrote: > On Sat, Jun 17, 2023 at 04:39:44PM +0800, Miaohe Lin wrote: >> On 2023/6/17 15:56, Mike Rapoport wrote: >>> On Sat, Jun 17, 2023 at 03:09:55PM +0800, Miaohe Lin wrote: >>>> HASH_SMALL only works when parameter numentries is 0. But the sole caller >>>> futex_init() never calls alloc_large_system_hash() with numentries set to >>>> 0. >>> >> >> Thanks for your quick review. >> >>> Doesn't it? >>> What happens when CONFIG_BASE_SMALL is set? >> >> When CONFIG_BASE_SMALL is set, futex_hashsize is set to 16 and alloc_large_system_hash() is called with >> numentries == 16 && flags == HASH_SMALL. But in the alloc_large_system_hash(), we have the below logic: >> >> alloc_large_system_hash() >> { >> if (!numentries) { /* numentries == 16 here, so this code block is skipped. */ >> ... >> if (unlikely(flags & HASH_SMALL)) { /* So as here. */ >> ... >> } >> ... >> } >> >> So HASH_SMALL is just unused. Or am I miss something? > > You are right, I've missed that. > >> Thanks. >> >>> >>>> So HASH_SMALL is obsolete and remove it. >>> >>>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> >>>> --- >>>> include/linux/memblock.h | 2 -- >>>> kernel/futex/core.c | 3 +-- >>>> mm/mm_init.c | 10 +--------- >>>> 3 files changed, 2 insertions(+), 13 deletions(-) >>>> >>>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >>>> index f71ff9f0ec81..346d80809517 100644 >>>> --- a/include/linux/memblock.h >>>> +++ b/include/linux/memblock.h >>>> @@ -581,8 +581,6 @@ extern void *alloc_large_system_hash(const char *tablename, >>>> unsigned long high_limit); >>>> >>>> #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ >>>> -#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min >>>> - * shift passed via *_hash_shift */ >>>> #define HASH_ZERO 0x00000004 /* Zero allocated hash table */ > > Can you update HASH_ZERO to 0x2? Will do. Thanks.
diff --git a/include/linux/memblock.h b/include/linux/memblock.h index f71ff9f0ec81..346d80809517 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -581,8 +581,6 @@ extern void *alloc_large_system_hash(const char *tablename, unsigned long high_limit); #define HASH_EARLY 0x00000001 /* Allocating during early boot? */ -#define HASH_SMALL 0x00000002 /* sub-page allocation allowed, min - * shift passed via *_hash_shift */ #define HASH_ZERO 0x00000004 /* Zero allocated hash table */ /* Only NUMA needs hash distribution. 64bit NUMA architectures have diff --git a/kernel/futex/core.c b/kernel/futex/core.c index 514e4582b863..f10587d1d481 100644 --- a/kernel/futex/core.c +++ b/kernel/futex/core.c @@ -1132,8 +1132,7 @@ static int __init futex_init(void) #endif futex_queues = alloc_large_system_hash("futex", sizeof(*futex_queues), - futex_hashsize, 0, - futex_hashsize < 256 ? HASH_SMALL : 0, + futex_hashsize, 0, 0, &futex_shift, NULL, futex_hashsize, futex_hashsize); futex_hashsize = 1UL << futex_shift; diff --git a/mm/mm_init.c b/mm/mm_init.c index d393631599a7..fab3c4649d5b 100644 --- a/mm/mm_init.c +++ b/mm/mm_init.c @@ -2492,15 +2492,7 @@ void *__init alloc_large_system_hash(const char *tablename, else numentries <<= (PAGE_SHIFT - scale); - /* Make sure we've got at least a 0-order allocation.. */ - if (unlikely(flags & HASH_SMALL)) { - /* Makes no sense without HASH_EARLY */ - WARN_ON(!(flags & HASH_EARLY)); - if (!(numentries >> *_hash_shift)) { - numentries = 1UL << *_hash_shift; - BUG_ON(!numentries); - } - } else if (unlikely((numentries * bucketsize) < PAGE_SIZE)) + if (unlikely((numentries * bucketsize) < PAGE_SIZE)) numentries = PAGE_SIZE / bucketsize; } numentries = roundup_pow_of_two(numentries);
HASH_SMALL only works when parameter numentries is 0. But the sole caller futex_init() never calls alloc_large_system_hash() with numentries set to 0. So HASH_SMALL is obsolete and remove it. Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> --- include/linux/memblock.h | 2 -- kernel/futex/core.c | 3 +-- mm/mm_init.c | 10 +--------- 3 files changed, 2 insertions(+), 13 deletions(-)