| Message ID | 5363876A.2030709@imgtec.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Fri, 2014-05-02 at 12:54 +0100, James Hogan wrote: > On 01/05/14 18:50, James Bottomley wrote: > > > >> + > >> +config MAX_STACK_SIZE_MB > >> + int "Maximum user stack size (MB)" > >> + default 80 > >> + range 8 256 if METAG > >> + range 8 2048 > >> + depends on STACK_GROWSUP > >> + help > >> + This is the maximum stack size in Megabytes in the VM layout of user > >> + processes when the stack grows upwards (currently only on parisc and > >> + metag arch). The stack will be located at the highest memory address > >> + minus the given value, unless the RLIMIT_STACK hard limit is changed > >> + to a smaller value in which case that is used. > >> + > >> + A sane initial value is 80 MB. > > > > There's one final issue with this: placement of the stack only really > > matters on 32 bits. We have three expanding memory areas: stack, heap > > and maps. On 64 bits these are placed well separated from each other on > > 64 bits, so an artificial limit like this doesn't matter. > > Does the following fixup diff look reasonable? It forces > MAX_STACK_SIZE_MB to 1024 and hides the Kconfig option for 64BIT, > effectively leaving the behaviour unchanged in that case. > > diff --git a/mm/Kconfig b/mm/Kconfig > index e80075979530..b0307f737bd7 100644 > --- a/mm/Kconfig > +++ b/mm/Kconfig > @@ -583,7 +583,8 @@ config GENERIC_EARLY_IOREMAP > bool > > config MAX_STACK_SIZE_MB > - int "Maximum user stack size (MB)" > + int "Maximum user stack size (MB)" if !64BIT > + default 1024 if 64BIT > default 80 > range 8 256 if METAG > range 8 2048 Yes, I think that's probably correct ... parisc doesn't actually have anything other than a testbed 64 bit userspace, so this is a bit theoretical for us. James -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 05/02/2014 04:48 PM, James Bottomley wrote: > On Fri, 2014-05-02 at 12:54 +0100, James Hogan wrote: >> On 01/05/14 18:50, James Bottomley wrote: >>> >>>> + >>>> +config MAX_STACK_SIZE_MB >>>> + int "Maximum user stack size (MB)" >>>> + default 80 >>>> + range 8 256 if METAG >>>> + range 8 2048 >>>> + depends on STACK_GROWSUP >>>> + help >>>> + This is the maximum stack size in Megabytes in the VM layout of user >>>> + processes when the stack grows upwards (currently only on parisc and >>>> + metag arch). The stack will be located at the highest memory address >>>> + minus the given value, unless the RLIMIT_STACK hard limit is changed >>>> + to a smaller value in which case that is used. >>>> + >>>> + A sane initial value is 80 MB. >>> >>> There's one final issue with this: placement of the stack only really >>> matters on 32 bits. We have three expanding memory areas: stack, heap >>> and maps. On 64 bits these are placed well separated from each other on >>> 64 bits, so an artificial limit like this doesn't matter. >> >> Does the following fixup diff look reasonable? It forces >> MAX_STACK_SIZE_MB to 1024 and hides the Kconfig option for 64BIT, >> effectively leaving the behaviour unchanged in that case. >> >> diff --git a/mm/Kconfig b/mm/Kconfig >> index e80075979530..b0307f737bd7 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -583,7 +583,8 @@ config GENERIC_EARLY_IOREMAP >> bool >> >> config MAX_STACK_SIZE_MB >> - int "Maximum user stack size (MB)" >> + int "Maximum user stack size (MB)" if !64BIT >> + default 1024 if 64BIT >> default 80 >> range 8 256 if METAG >> range 8 2048 > > Yes, I think that's probably correct ... No, it's not correct. It will then choose then a 1GB stack for compat tasks on 64bit kernel. Helge > parisc doesn't actually have > anything other than a testbed 64 bit userspace, so this is a bit > theoretical for us. -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/mm/Kconfig b/mm/Kconfig index e80075979530..b0307f737bd7 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -583,7 +583,8 @@ config GENERIC_EARLY_IOREMAP bool config MAX_STACK_SIZE_MB - int "Maximum user stack size (MB)" + int "Maximum user stack size (MB)" if !64BIT + default 1024 if 64BIT default 80 range 8 256 if METAG range 8 2048