| Message ID | 543EAC5A.6050209@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Oct 15, 2014 at 08:18:18PM +0300, Grygorii Strashko wrote: > 3) If I apply below change - I can boot: > diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c > index c031063..85ad92b 100644 > --- a/arch/arm/kernel/setup.c > +++ b/arch/arm/kernel/setup.c > @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) > > early_paging_init(mdesc, lookup_processor_type(read_cpuid_id())); > setup_dma_zone(mdesc); > - sanity_check_meminfo(); > arm_memblock_init(mdesc); > + sanity_check_meminfo(); > > paging_init(mdesc); > request_standard_resources(mdesc); > > ^^ not sure if it totally safe, because dma_contiguous_reserve(arm_dma_limit); > is called from inside arm_memblock_init() and it does bootmem allocations. It isn't. sanity_check_meminfo() _must_ be called before arm_memblock_init() so that sanity_check_meminfo() can adjust the passed memory description to remove stuff which is inappropriate for the configuration, before it is passed to memblock. > Sort Summary: > It looks like all static memory reservation and memory stealing's > (calling of memblock_remove()) have to be done before any other > operations and before calculating ARM memory limits. No, that should not be the case. The way it is /supposed/ to work is: - We obtain the memory information and pass it into memblock - We sanity check the memory in memblock, removing memory which we deem to be unacceptable for the kernel configuration via memblock_remove(). Also calculate the highest address we are prepared to allocate, which is set to the top of the first chunk of memory, or the top of lowmem. - We then see about reserving memory from memblock. This marks memory as reserved, or in certain cases where we actually want to prevent the kernel taking control of the memory, we completely remove the memory from memblock (via memblock_remove). Memory removed via memblock_remove() is then not available for any allocations, and should not be touched by the kernel in any way from that point on. It doesn't matter that the memblock limit is still set higher, because the memory has been removed from the available memory pool, it should not be allocated.
Hi Russell, On 10/15/2014 08:50 PM, Russell King - ARM Linux wrote: > On Wed, Oct 15, 2014 at 08:18:18PM +0300, Grygorii Strashko wrote: >> 3) If I apply below change - I can boot: >> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >> index c031063..85ad92b 100644 >> --- a/arch/arm/kernel/setup.c >> +++ b/arch/arm/kernel/setup.c >> @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) >> >> early_paging_init(mdesc, lookup_processor_type(read_cpuid_id())); >> setup_dma_zone(mdesc); >> - sanity_check_meminfo(); >> arm_memblock_init(mdesc); >> + sanity_check_meminfo(); >> >> paging_init(mdesc); >> request_standard_resources(mdesc); >> >> ^^ not sure if it totally safe, because dma_contiguous_reserve(arm_dma_limit); >> is called from inside arm_memblock_init() and it does bootmem allocations. > > It isn't. sanity_check_meminfo() _must_ be called before arm_memblock_init() > so that sanity_check_meminfo() can adjust the passed memory description to > remove stuff which is inappropriate for the configuration, before it is > passed to memblock. > >> Sort Summary: >> It looks like all static memory reservation and memory stealing's >> (calling of memblock_remove()) have to be done before any other >> operations and before calculating ARM memory limits. > > No, that should not be the case. The way it is /supposed/ to work is: > > - We obtain the memory information and pass it into memblock > - We sanity check the memory in memblock, removing memory which we > deem to be unacceptable for the kernel configuration via > memblock_remove(). Also calculate the highest address we are > prepared to allocate, which is set to the top of the first chunk > of memory, or the top of lowmem. > - We then see about reserving memory from memblock. This marks memory > as reserved, or in certain cases where we actually want to prevent > the kernel taking control of the memory, we completely remove the > memory from memblock (via memblock_remove). In my case amount of removed memory is so high that there is no room for Highmem anymore. memblock.memory.regions[0].base + size < arm_lowmem_limit and arm_lowmem_limit == memblock.current_limit > > Memory removed via memblock_remove() is then not available for any > allocations, and should not be touched by the kernel in any way from > that point on. > > It doesn't matter that the memblock limit is still set higher, because > the memory has been removed from the available memory pool, it should > not be allocated. > You are right in general, but seems problem is not in memblock itself :( The problem is with memory control variables like: - arm_lowmem_limit - max_low_pfn - max_pfn The last thing I've found that issue happens when in bootmem_init()->find_limits() the max_low variable got value greater than max_high: max_low_pfn > max_pfn. Then kernel crashes somewhere inside free_all_bootmem(); Below hack allows to boot: +++ b/arch/arm/mm/init.c @@ -140,6 +140,8 @@ static void __init find_limits(unsigned long *min, unsigned long *max_low, *max_low = PFN_DOWN(memblock_get_current_limit()); *min = PFN_UP(memblock_start_of_DRAM()); *max_high = PFN_DOWN(memblock_end_of_DRAM()); + if (*max_low > *max_high) + *max_low = *max_high; } Regards, -grygorii
On 10/16/2014 10:32 AM, Grygorii Strashko wrote: > Hi Russell, > On 10/15/2014 08:50 PM, Russell King - ARM Linux wrote: >> On Wed, Oct 15, 2014 at 08:18:18PM +0300, Grygorii Strashko wrote: >>> 3) If I apply below change - I can boot: >>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >>> index c031063..85ad92b 100644 >>> --- a/arch/arm/kernel/setup.c >>> +++ b/arch/arm/kernel/setup.c >>> @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) >>> >>> early_paging_init(mdesc, lookup_processor_type(read_cpuid_id())); >>> setup_dma_zone(mdesc); >>> - sanity_check_meminfo(); >>> arm_memblock_init(mdesc); >>> + sanity_check_meminfo(); >>> >>> paging_init(mdesc); >>> request_standard_resources(mdesc); >>> >>> ^^ not sure if it totally safe, because dma_contiguous_reserve(arm_dma_limit); >>> is called from inside arm_memblock_init() and it does bootmem allocations. >> >> It isn't. sanity_check_meminfo() _must_ be called before arm_memblock_init() >> so that sanity_check_meminfo() can adjust the passed memory description to >> remove stuff which is inappropriate for the configuration, before it is >> passed to memblock. >> >>> Sort Summary: >>> It looks like all static memory reservation and memory stealing's >>> (calling of memblock_remove()) have to be done before any other >>> operations and before calculating ARM memory limits. >> >> No, that should not be the case. The way it is /supposed/ to work is: >> >> - We obtain the memory information and pass it into memblock >> - We sanity check the memory in memblock, removing memory which we >> deem to be unacceptable for the kernel configuration via >> memblock_remove(). Also calculate the highest address we are >> prepared to allocate, which is set to the top of the first chunk >> of memory, or the top of lowmem. >> - We then see about reserving memory from memblock. This marks memory >> as reserved, or in certain cases where we actually want to prevent >> the kernel taking control of the memory, we completely remove the >> memory from memblock (via memblock_remove). > > In my case amount of removed memory is so high that there is no room > for Highmem anymore. > > memblock.memory.regions[0].base + size < arm_lowmem_limit > and arm_lowmem_limit == memblock.current_limit > >> >> Memory removed via memblock_remove() is then not available for any >> allocations, and should not be touched by the kernel in any way from >> that point on. >> >> It doesn't matter that the memblock limit is still set higher, because >> the memory has been removed from the available memory pool, it should >> not be allocated. >> > > You are right in general, but seems problem is not in memblock itself :( > The problem is with memory control variables like: > - arm_lowmem_limit > - max_low_pfn > - max_pfn > > The last thing I've found that issue happens when in > bootmem_init()->find_limits() the max_low variable got value greater than > max_high: max_low_pfn > max_pfn. > > Then kernel crashes somewhere inside free_all_bootmem(); > > Below hack allows to boot: > +++ b/arch/arm/mm/init.c > @@ -140,6 +140,8 @@ static void __init find_limits(unsigned long *min, unsigned long *max_low, > *max_low = PFN_DOWN(memblock_get_current_limit()); > *min = PFN_UP(memblock_start_of_DRAM()); > *max_high = PFN_DOWN(memblock_end_of_DRAM()); > + if (*max_low > *max_high) > + *max_low = *max_high; > } Can you print out the values of max_low, min, max_high and call __memblock_dump_all() at this point in time? It would also be helpful to get the pr_debug print outs in drivers/of/of_reserved_mem.c to see what's being reserved there. FWIW, I've tested something similar and it worked correctly but there are at least two big differences in the case here 1) Removing the top of memory instead of just a block in the middle 2) Working above 32 bit ranges. Eliminating #2 here may be difficult but can you try just removing 256MB instead of 512MB? (reg = <0x8 0x20000000 0x0 0x10000000>) Thanks, Laura
Hi Laura, On 10/17/2014 12:10 PM, Laura Abbott wrote: > On 10/16/2014 10:32 AM, Grygorii Strashko wrote: >> Hi Russell, >> On 10/15/2014 08:50 PM, Russell King - ARM Linux wrote: >>> On Wed, Oct 15, 2014 at 08:18:18PM +0300, Grygorii Strashko wrote: >>>> 3) If I apply below change - I can boot: >>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >>>> index c031063..85ad92b 100644 >>>> --- a/arch/arm/kernel/setup.c >>>> +++ b/arch/arm/kernel/setup.c >>>> @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) >>>> >>>> early_paging_init(mdesc, >>>> lookup_processor_type(read_cpuid_id())); >>>> setup_dma_zone(mdesc); >>>> - sanity_check_meminfo(); >>>> arm_memblock_init(mdesc); >>>> + sanity_check_meminfo(); >>>> >>>> paging_init(mdesc); >>>> request_standard_resources(mdesc); >>>> >>>> ^^ not sure if it totally safe, because >>>> dma_contiguous_reserve(arm_dma_limit); >>>> is called from inside arm_memblock_init() and it does bootmem >>>> allocations. >>> >>> It isn't. sanity_check_meminfo() _must_ be called before >>> arm_memblock_init() >>> so that sanity_check_meminfo() can adjust the passed memory >>> description to >>> remove stuff which is inappropriate for the configuration, before it is >>> passed to memblock. >>> >>>> Sort Summary: >>>> It looks like all static memory reservation and memory stealing's >>>> (calling of memblock_remove()) have to be done before any other >>>> operations and before calculating ARM memory limits. >>> >>> No, that should not be the case. The way it is /supposed/ to work is: >>> >>> - We obtain the memory information and pass it into memblock >>> - We sanity check the memory in memblock, removing memory which we >>> deem to be unacceptable for the kernel configuration via >>> memblock_remove(). Also calculate the highest address we are >>> prepared to allocate, which is set to the top of the first chunk >>> of memory, or the top of lowmem. >>> - We then see about reserving memory from memblock. This marks memory >>> as reserved, or in certain cases where we actually want to prevent >>> the kernel taking control of the memory, we completely remove the >>> memory from memblock (via memblock_remove). >> >> In my case amount of removed memory is so high that there is no room >> for Highmem anymore. >> >> memblock.memory.regions[0].base + size < arm_lowmem_limit >> and arm_lowmem_limit == memblock.current_limit >> >>> >>> Memory removed via memblock_remove() is then not available for any >>> allocations, and should not be touched by the kernel in any way from >>> that point on. >>> >>> It doesn't matter that the memblock limit is still set higher, because >>> the memory has been removed from the available memory pool, it should >>> not be allocated. >>> >> >> You are right in general, but seems problem is not in memblock itself :( >> The problem is with memory control variables like: >> - arm_lowmem_limit >> - max_low_pfn >> - max_pfn >> >> The last thing I've found that issue happens when in >> bootmem_init()->find_limits() the max_low variable got value greater than >> max_high: max_low_pfn > max_pfn. >> >> Then kernel crashes somewhere inside free_all_bootmem(); >> >> Below hack allows to boot: >> +++ b/arch/arm/mm/init.c >> @@ -140,6 +140,8 @@ static void __init find_limits(unsigned long *min, >> unsigned long *max_low, >> *max_low = PFN_DOWN(memblock_get_current_limit()); >> *min = PFN_UP(memblock_start_of_DRAM()); >> *max_high = PFN_DOWN(memblock_end_of_DRAM()); >> + if (*max_low > *max_high) >> + *max_low = *max_high; >> } > > Can you print out the values of max_low, min, max_high and call > __memblock_dump_all() at this point in time? It would also > be helpful to get the pr_debug print outs in > drivers/of/of_reserved_mem.c to see what's being reserved there. As I mentioned in first e-mail I've 1G Mem node initially: reg = <0x8 0x00000000 0x0 0x40000000>; and have memory reservation of 512M in the upper part of memory: reserved-memory { reg = <0x8 0x20000000 0x0 0x20000000>; then in sanity_check_meminfo() initial mem configuration calculated as following: [ 0.000000] ======= memblock_limit=0x000000082f800000 arm_lowmem_limit=0x000000082f800000 vmalloc_limit=ef800000 high_memory=0x000000082f800000 and memblock.current_limit == arm_lowmem_limit=0x000000082f800000 then in arm_memblock_init()->early_init_fdt_scan_reserved_mem() 512M of memory removed (not reserved!, because "no-map;" is defined). After that Kernel will have only 512M of accessible memory memory[0x0] [0x00000800000000-0x0000081fffffff] I've checked of_reserved_mem.c and saw no issues there :( Bad case: [ 0.000000] ======= min_low_pfn=800000 max_low_pfn=82F800 max_pfn=820000 [ 0.000000] MEMBLOCK configuration: [ 0.000000] memory size = 0x20000000 reserved size = 0x273f08c [ 0.000000] memory.cnt = 0x1 [ 0.000000] memory[0x0] [0x00000800000000-0x0000081fffffff], 0x20000000 bytes flags: 0x0 [ 0.000000] reserved.cnt = 0x15 [ 0.000000] reserved[0x0] [0x00000800003000-0x00000800007fff], 0x5000 bytes flags: 0x0 [ 0.000000] reserved[0x1] [0x00000800008300-0x000008007771df], 0x76eee0 bytes flags: 0x0 [ 0.000000] reserved[0x2] [0x00000802000000-0x000008028fffff], 0x900000 bytes flags: 0x0 [ 0.000000] reserved[0x3] [0x00000807000000-0x00000807008ebd], 0x8ebe bytes flags: 0x0 [ 0.000000] reserved[0x4] [0x0000081e93d000-0x0000081e9ccfff], 0x90000 bytes flags: 0x0 [ 0.000000] reserved[0x5] [0x0000081e9cd080-0x0000081e9cf07f], 0x2000 bytes flags: 0x0 [ 0.000000] reserved[0x6] [0x0000081e9cf0bc-0x0000081ebecfe3], 0x21df28 bytes flags: 0x0 [ 0.000000] reserved[0x7] [0x0000081ebed000-0x0000081effefff], 0x412000 bytes flags: 0x0 [ 0.000000] reserved[0x8] [0x0000081efffa40-0x0000081efffa83], 0x44 bytes flags: 0x0 [ 0.000000] reserved[0x9] [0x0000081efffac0-0x0000081efffb03], 0x44 bytes flags: 0x0 [ 0.000000] reserved[0xa] [0x0000081efffb40-0x0000081efffbb7], 0x78 bytes flags: 0x0 [ 0.000000] reserved[0xb] [0x0000081efffbc0-0x0000081efffbcf], 0x10 bytes flags: 0x0 [ 0.000000] reserved[0xc] [0x0000081efffc00-0x0000081efffc0f], 0x10 bytes flags: 0x0 [ 0.000000] reserved[0xd] [0x0000081efffc40-0x0000081efffc43], 0x4 bytes flags: 0x0 [ 0.000000] reserved[0xe] [0x0000081efffc80-0x0000081efffc83], 0x4 bytes flags: 0x0 [ 0.000000] reserved[0xf] [0x0000081efffcc0-0x0000081efffd48], 0x89 bytes flags: 0x0 [ 0.000000] reserved[0x10] [0x0000081efffd80-0x0000081efffe08], 0x89 bytes flags: 0x0 [ 0.000000] reserved[0x11] [0x0000081efffe40-0x0000081efffec8], 0x89 bytes flags: 0x0 [ 0.000000] reserved[0x12] [0x0000081efffee4-0x0000081efffefe], 0x1b bytes flags: 0x0 [ 0.000000] reserved[0x13] [0x0000081effff00-0x0000081effff27], 0x28 bytes flags: 0x0 [ 0.000000] reserved[0x14] [0x0000081effff40-0x0000081fffffff], 0x10000c0 bytes flags: 0x0 [ 0.000000] =====================================free_all_bootmem and system stuck in free_all_bootmem: [...] [ 0.000000] =====================================__free_memory_core 0x0000000802900000 0x0000000807000000 [ 0.000000] =====================================__free_pages_memory 802900 807000 [ 0.000000] =====================================__free_pages_bootmem dec42000 8 [ 0.000000] =====================================__free_pages_memory 802A00 807000 [ 0.000000] =====================================__free_pages_bootmem dec44000 9 [ 0.000000] =====================================__free_pages_memory 802C00 807000 [ 0.000000] =====================================__free_pages_bootmem dec48000 10 [ 0.000000] =====================================__free_pages_memory 803000 807000 [ 0.000000] =====================================__free_pages_bootmem dec50000 10 [ 0.000000] =====================================__free_pages_memory 803400 807000 [ 0.000000] =====================================__free_pages_bootmem dec58000 10 [ 0.000000] =====================================__free_pages_memory 803800 807000 [ 0.000000] =====================================__free_pages_bootmem dec60000 10 [ 0.000000] =====================================__free_pages_memory 803C00 807000 [ 0.000000] =====================================__free_pages_bootmem dec68000 10 [ 0.000000] =====================================__free_pages_memory 804000 807000 [ 0.000000] =====================================__free_pages_bootmem dec70000 10 [ 0.000000] =====================================__free_pages_memory 804400 807000 [ 0.000000] =====================================__free_pages_bootmem dec78000 10 [ 0.000000] =====================================__free_pages_memory 804800 807000 [ 0.000000] =====================================__free_pages_bootmem dec80000 10 [ 0.000000] =====================================__free_pages_memory 804C00 807000 [ 0.000000] =====================================__free_pages_bootmem dec88000 10 [ 0.000000] =====================================__free_pages_memory 805000 807000 [ 0.000000] =====================================__free_pages_bootmem dec90000 10 [ 0.000000] =====================================__free_pages_memory 805400 807000 [ 0.000000] =====================================__free_pages_bootmem dec98000 10 [ 0.000000] =====================================__free_pages_memory 805800 807000 [ 0.000000] =====================================__free_pages_bootmem deca0000 10 [ 0.000000] =====================================__free_pages_memory 805C00 807000 [ 0.000000] =====================================__free_pages_bootmem deca8000 10 [ 0.000000] =====================================__free_pages_memory 806000 807000 [ 0.000000] =====================================__free_pages_bootmem decb0000 10 ^^ Good case: [ 0.000000] ======= min_low_pfn=800000 max_low_pfn=820000 max_pfn=820000 [ 0.000000] MEMBLOCK configuration: [ 0.000000] memory size = 0x20000000 reserved size = 0x2531888 [ 0.000000] memory.cnt = 0x1 [ 0.000000] memory[0x0] [0x00000800000000-0x0000081fffffff], 0x20000000 bytes flags: 0x0 [ 0.000000] reserved.cnt = 0x13 [ 0.000000] reserved[0x0] [0x00000800003000-0x00000800007fff], 0x5000 bytes flags: 0x0 [ 0.000000] reserved[0x1] [0x00000800008300-0x000008007771df], 0x76eee0 bytes flags: 0x0 [ 0.000000] reserved[0x2] [0x00000802000000-0x000008028fffff], 0x900000 bytes flags: 0x0 [ 0.000000] reserved[0x3] [0x00000807000000-0x00000807008ebd], 0x8ebe bytes flags: 0x0 [ 0.000000] reserved[0x4] [0x0000081eb4a000-0x0000081ebd9fff], 0x90000 bytes flags: 0x0 [ 0.000000] reserved[0x5] [0x0000081ebda880-0x0000081ebdc87f], 0x2000 bytes flags: 0x0 [ 0.000000] reserved[0x6] [0x0000081ebdc8bc-0x0000081effefff], 0x422744 bytes flags: 0x0 [ 0.000000] reserved[0x7] [0x0000081efffa80-0x0000081efffac3], 0x44 bytes flags: 0x0 [ 0.000000] reserved[0x8] [0x0000081efffb00-0x0000081efffb43], 0x44 bytes flags: 0x0 [ 0.000000] reserved[0x9] [0x0000081efffb80-0x0000081efffbf7], 0x78 bytes flags: 0x0 [ 0.000000] reserved[0xa] [0x0000081efffc00-0x0000081efffc0f], 0x10 bytes flags: 0x0 [ 0.000000] reserved[0xb] [0x0000081efffc40-0x0000081efffc4f], 0x10 bytes flags: 0x0 [ 0.000000] reserved[0xc] [0x0000081efffc80-0x0000081efffc83], 0x4 bytes flags: 0x0 [ 0.000000] reserved[0xd] [0x0000081efffcc0-0x0000081efffd48], 0x89 bytes flags: 0x0 [ 0.000000] reserved[0xe] [0x0000081efffd80-0x0000081efffe08], 0x89 bytes flags: 0x0 [ 0.000000] reserved[0xf] [0x0000081efffe40-0x0000081efffec8], 0x89 bytes flags: 0x0 [ 0.000000] reserved[0x10] [0x0000081effff00-0x0000081effff27], 0x28 bytes flags: 0x0 [ 0.000000] reserved[0x11] [0x0000081effff40-0x0000081effff9e], 0x5f bytes flags: 0x0 [ 0.000000] reserved[0x12] [0x0000081effffa0-0x0000081fffffff], 0x1000060 bytes flags: 0x0 [ 0.000000] =====================================free_all_bootmem Also, there is additional log message in bad case: [ 0.000000] HighMem zone: 1048080 pages exceeds freesize 0 > > FWIW, I've tested something similar and it worked correctly but > there are at least two big differences in the case here > 1) Removing the top of memory instead of just a block in the middle > 2) Working above 32 bit ranges. > > Eliminating #2 here may be difficult but can you try just removing > 256MB instead of 512MB? (reg = <0x8 0x20000000 0x0 0x10000000>) I think, that this issue can be reproduced on any ARM platform with one membank - all you need is to just truncate memory from DT using "reserved-memory" + "no-map;" node in the way that memblock.memory.regions[0].base + size < arm_lowmem_limit and there will be no room for Highmem. Regards, -grygorii
On 10/16/2014 10:32 AM, Grygorii Strashko wrote: > Hi Russell, > On 10/15/2014 08:50 PM, Russell King - ARM Linux wrote: >> On Wed, Oct 15, 2014 at 08:18:18PM +0300, Grygorii Strashko wrote: >>> 3) If I apply below change - I can boot: >>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >>> index c031063..85ad92b 100644 >>> --- a/arch/arm/kernel/setup.c >>> +++ b/arch/arm/kernel/setup.c >>> @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) >>> >>> early_paging_init(mdesc, lookup_processor_type(read_cpuid_id())); >>> setup_dma_zone(mdesc); >>> - sanity_check_meminfo(); >>> arm_memblock_init(mdesc); >>> + sanity_check_meminfo(); >>> >>> paging_init(mdesc); >>> request_standard_resources(mdesc); >>> >>> ^^ not sure if it totally safe, because dma_contiguous_reserve(arm_dma_limit); >>> is called from inside arm_memblock_init() and it does bootmem allocations. >> >> It isn't. sanity_check_meminfo() _must_ be called before arm_memblock_init() >> so that sanity_check_meminfo() can adjust the passed memory description to >> remove stuff which is inappropriate for the configuration, before it is >> passed to memblock. >> >>> Sort Summary: >>> It looks like all static memory reservation and memory stealing's >>> (calling of memblock_remove()) have to be done before any other >>> operations and before calculating ARM memory limits. >> >> No, that should not be the case. The way it is /supposed/ to work is: >> >> - We obtain the memory information and pass it into memblock >> - We sanity check the memory in memblock, removing memory which we >> deem to be unacceptable for the kernel configuration via >> memblock_remove(). Also calculate the highest address we are >> prepared to allocate, which is set to the top of the first chunk >> of memory, or the top of lowmem. >> - We then see about reserving memory from memblock. This marks memory >> as reserved, or in certain cases where we actually want to prevent >> the kernel taking control of the memory, we completely remove the >> memory from memblock (via memblock_remove). > > In my case amount of removed memory is so high that there is no room > for Highmem anymore. > > memblock.memory.regions[0].base + size < arm_lowmem_limit > and arm_lowmem_limit == memblock.current_limit > >> >> Memory removed via memblock_remove() is then not available for any >> allocations, and should not be touched by the kernel in any way from >> that point on. >> >> It doesn't matter that the memblock limit is still set higher, because >> the memory has been removed from the available memory pool, it should >> not be allocated. >> > > You are right in general, but seems problem is not in memblock itself :( > The problem is with memory control variables like: > - arm_lowmem_limit > - max_low_pfn > - max_pfn > > The last thing I've found that issue happens when in > bootmem_init()->find_limits() the max_low variable got value greater than > max_high: max_low_pfn > max_pfn. > Without getting too much into details, I don't see much point to let kernel know about memory and then just to remove a huge block of it which is it never gonna see it. It creates hole in Linear memory which you can avoid by doing that memory partition and letting kernel know about memory which it needs to deal with it. If you are just playing around then its fine. Regards, Santosh
On 10/17/2014 3:21 AM, Grygorii Strashko wrote: > Hi Laura, > > As I mentioned in first e-mail I've 1G Mem node initially: > reg = <0x8 0x00000000 0x0 0x40000000>; > > and have memory reservation of 512M in the upper part of memory: > reserved-memory { > reg = <0x8 0x20000000 0x0 0x20000000>; > > then in sanity_check_meminfo() initial mem configuration calculated as following: > > [ 0.000000] ======= memblock_limit=0x000000082f800000 arm_lowmem_limit=0x000000082f800000 vmalloc_limit=ef800000 high_memory=0x000000082f800000 > and memblock.current_limit == arm_lowmem_limit=0x000000082f800000 > > then in arm_memblock_init()->early_init_fdt_scan_reserved_mem() 512M of memory removed > (not reserved!, because "no-map;" is defined). > > After that Kernel will have only 512M of accessible memory > memory[0x0] [0x00000800000000-0x0000081fffffff] > > I've checked of_reserved_mem.c and saw no issues there :( > Yes, I suspect the issue is not with of_reserved_mem.c and instead with sanity_check_meminfo in mmu.c . I'm still traveling so I'll probably take a look on Monday unless I find some time sooner. Thanks, Laura
On 10/17/2014 02:36 PM, Santosh Shilimkar wrote: > On 10/16/2014 10:32 AM, Grygorii Strashko wrote: >> Hi Russell, >> On 10/15/2014 08:50 PM, Russell King - ARM Linux wrote: >>> On Wed, Oct 15, 2014 at 08:18:18PM +0300, Grygorii Strashko wrote: >>>> 3) If I apply below change - I can boot: >>>> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c >>>> index c031063..85ad92b 100644 >>>> --- a/arch/arm/kernel/setup.c >>>> +++ b/arch/arm/kernel/setup.c >>>> @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) >>>> >>>> early_paging_init(mdesc, >>>> lookup_processor_type(read_cpuid_id())); >>>> setup_dma_zone(mdesc); >>>> - sanity_check_meminfo(); >>>> arm_memblock_init(mdesc); >>>> + sanity_check_meminfo(); >>>> >>>> paging_init(mdesc); >>>> request_standard_resources(mdesc); >>>> >>>> ^^ not sure if it totally safe, because >>>> dma_contiguous_reserve(arm_dma_limit); >>>> is called from inside arm_memblock_init() and it does bootmem >>>> allocations. >>> >>> It isn't. sanity_check_meminfo() _must_ be called before >>> arm_memblock_init() >>> so that sanity_check_meminfo() can adjust the passed memory >>> description to >>> remove stuff which is inappropriate for the configuration, before it is >>> passed to memblock. >>> >>>> Sort Summary: >>>> It looks like all static memory reservation and memory stealing's >>>> (calling of memblock_remove()) have to be done before any other >>>> operations and before calculating ARM memory limits. >>> >>> No, that should not be the case. The way it is /supposed/ to work is: >>> >>> - We obtain the memory information and pass it into memblock >>> - We sanity check the memory in memblock, removing memory which we >>> deem to be unacceptable for the kernel configuration via >>> memblock_remove(). Also calculate the highest address we are >>> prepared to allocate, which is set to the top of the first chunk >>> of memory, or the top of lowmem. >>> - We then see about reserving memory from memblock. This marks memory >>> as reserved, or in certain cases where we actually want to prevent >>> the kernel taking control of the memory, we completely remove the >>> memory from memblock (via memblock_remove). >> >> In my case amount of removed memory is so high that there is no room >> for Highmem anymore. >> >> memblock.memory.regions[0].base + size < arm_lowmem_limit >> and arm_lowmem_limit == memblock.current_limit >> >>> >>> Memory removed via memblock_remove() is then not available for any >>> allocations, and should not be touched by the kernel in any way from >>> that point on. >>> >>> It doesn't matter that the memblock limit is still set higher, because >>> the memory has been removed from the available memory pool, it should >>> not be allocated. >>> >> >> You are right in general, but seems problem is not in memblock itself :( >> The problem is with memory control variables like: >> - arm_lowmem_limit >> - max_low_pfn >> - max_pfn >> >> The last thing I've found that issue happens when in >> bootmem_init()->find_limits() the max_low variable got value greater than >> max_high: max_low_pfn > max_pfn. >> > Without getting too much into details, I don't see much point to let > kernel know about memory and then just to remove a huge block of it > which is it never gonna see it. It creates hole in Linear memory > which you can avoid by doing that memory partition and letting kernel > know about memory which it needs to deal with it. > > If you are just playing around then its fine. Oh. Yes you are right in general - I've just not expected from kernel to crash silently, so my intention was to report issue first of all. Regards, -grygorii
On Tue, Oct 21, 2014 at 08:02:27PM +0300, Grygorii Strashko wrote: > Oh. Yes you are right in general - I've just not expected from kernel > to crash silently, so my intention was to report issue first of all. The problem here is that each time someone finds a new way to break it, the code gets more complicated, which means there's yet more ways to break it. As an example, try reading through sanity_check_meminfo() and working out exactly what each variable in there does - it'll take some considerable time to work it out. It /used/ to be pretty obvious. It's pretty scary too that it's walking a list of memblock regions, while modifying that list, potentially removing the entry that it's currently at. I suspect that would cause it to skip a region given how the for() loop works. Either way, I think we need to get some of this stuff back to being coded in a simple and obvious-to-understand manner.
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c index c031063..85ad92b 100644 --- a/arch/arm/kernel/setup.c +++ b/arch/arm/kernel/setup.c @@ -917,8 +917,8 @@ void __init setup_arch(char **cmdline_p) early_paging_init(mdesc, lookup_processor_type(read_cpuid_id())); setup_dma_zone(mdesc); - sanity_check_meminfo(); arm_memblock_init(mdesc); + sanity_check_meminfo(); paging_init(mdesc); request_standard_resources(mdesc);
Hi All, I did some experiments with memory reservation from DT and got boot failure. Input data: - Platform Keystone 2 K2HK - LPAE enabled - RAM 1G: memory { reg = <0x8 0x00000000 0x0 0x40000000>; }; - memory reservation 512M: reserved-memory { #address-cells = <2>; #size-cells = <2>; ranges; dspsmem: dspsmem@20000000 { reg = <0x8 0x20000000 0x0 0x20000000>; no-map; }; }; So, total memory available for Kernel should be 512M, below is memory state for the case when memory is reserved from u-boot: [ 0.000000] Memory: 486200K/524288K available (5085K kernel code, 265K rwdata, 1776K rodata, 296K init, 178K bss, 38088K reserved, 0K highmem) [ 0.000000] Virtual kernel memory layout: [ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB) [ 0.000000] fixmap : 0xffc00000 - 0xffe00000 (2048 kB) [ 0.000000] vmalloc : 0xe0800000 - 0xff000000 ( 488 MB) [ 0.000000] lowmem : 0xc0000000 - 0xe0000000 ( 512 MB) [ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB) [ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB) [ 0.000000] .text : 0xc0008000 - 0xc06bb8a4 (6863 kB) [ 0.000000] .init : 0xc06bc000 - 0xc0706000 ( 296 kB) [ 0.000000] .data : 0xc0706000 - 0xc07485fc ( 266 kB) [ 0.000000] .bss : 0xc07485fc - 0xc07751e0 ( 179 kB) Why: - I'm trying to reserve memory from kernel instead of u-boot. Fast ;( investigation results: 1) The issue happens only if no-map; is used. In this case FDT code will call memblock_remove() instead of memblock_reserve(). 2) ARM limits are set wrongly from sanity_check_meminfo(): [ 0.000000] ======= memblock_limit=0x000000082f800000 arm_lowmem_limit=0x000000082f800000 vmalloc_limit=ef800000 high_memory=0x000000082f800000 instead of [ 0.000000] ======= memblock_limit=0x0000000820000000 arm_lowmem_limit=0x0000000820000000 vmalloc_limit=e0000000 high_memory=0x000000082f800000 3) If I apply below change - I can boot: ^^ not sure if it totally safe, because dma_contiguous_reserve(arm_dma_limit); is called from inside arm_memblock_init() and it does bootmem allocations. Sort Summary: It looks like all static memory reservation and memory stealing's (calling of memblock_remove()) have to be done before any other operations and before calculating ARM memory limits. Thank you for any comments. Regards, -grygorii