From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hogan Subject: Re: [PATCH] parisc,metag: Do not hardcode maximum userspace stack size Date: Tue, 13 May 2014 23:52:44 +0100 Message-ID: <5372A23C.702@imgtec.com> References: <20140430212602.GA20601@p100.fritz.box> <53622DBA.807@imgtec.com> <1398966636.2174.21.camel@dabdike> <5363876A.2030709@imgtec.com> <1399042116.2202.1.camel@dabdike> <5365EC05.5080900@gmx.de> <5371FF97.7030205@imgtec.com> <5372764A.2060906@gmx.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Cc: , , "John David Anglin" , To: Helge Deller , James Bottomley Return-path: In-Reply-To: <5372764A.2060906@gmx.de> List-ID: List-Id: linux-parisc.vger.kernel.org Hi Helge, On 13/05/14 20:45, Helge Deller wrote: > On 05/13/2014 01:18 PM, James Hogan wrote: >> On 04/05/14 08:28, Helge Deller wrote: >>> 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. >> >> Sorry for the delay (I had most of last week off sick and still catching >> up). > > No problem. > >> That's a good point. It makes me think the best way to handle it is in a >> new definition in asm/processor.h, maybe STACK_SIZE_MAX. Does something >> like this look better? This patch isn't getting any cleaner >> unfortunately. > > > Yes, it's correct now. > Just tested it. Thanks! Thanks. > Another problem: > I think you wanted to get it backported into older kernels? Yeh, back to v3.9 ideally. > It seems the changes to mm/Kconfig will not apply cleanly to 3.14 or lower, Hmm, I guess the patch could be split easily though such that METAG always defined STACK_SIZE_MAX as 256MB and parisc always as 1GB (i.e. minimal fix for metag without actually changing any stack sizes), then have a second patch (not for stable) to make it match the v3 patch. I'll try that (I probably should have done that in the first place). Thanks James > and the changes to arch/parisc/kernel/sys_parisc.c will not apply to 3.13 or lower... > > Maybe cleaning up the patch to apply cleanly to 3.14 would make sense > and ignore older kernels? > > Helge > > >> From 6ecb0392a3b670c4bf1641a6ec56f22427ca8b57 Mon Sep 17 00:00:00 2001 >> From: Helge Deller >> Date: Wed, 30 Apr 2014 23:26:02 +0200 >> Subject: [PATCH 1/1] parisc,metag: Do not hardcode maximum userspace stack >> size >> >> This patch affects only architectures where the stack grows upwards >> (currently parisc and metag only). On those do not hardcode the maximum >> initial stack size to 1GB for 32-bit processes, but make it configurable >> via a config option. >> >> The main problem with the hardcoded stack size is, that we have two >> memory regions which grow upwards: stack and heap. To keep most of the >> memory available for heap in a flexmap memoy layout, it makes no sense >> to hard allocate up to 1GB of the memory for stack which can't be used >> as heap then. >> >> This patch makes the stack size configurable and uses 80MB as default >> value which has been in use during the last few years on parisc and >> which didn't showed any problems yet. >> >> This also fixes a BUG on metag if the RLIMIT_STACK hard limit is >> increased beyond a safe value by root. E.g. when starting a process >> after running "ulimit -H -s unlimited" it will then attempt to use a >> stack size of the maximum 1GB which is far too big for metag's limited >> user virtual address space (stack_top is usually 0x3ffff000): >> BUG: failure at fs/exec.c:589/shift_arg_pages()! >> >> Signed-off-by: Helge Deller >> Signed-off-by: James Hogan >> Cc: linux-parisc@vger.kernel.org >> Cc: linux-metag@vger.kernel.org >> Cc: John David Anglin >> Cc: stable@vger.kernel.org # only needed for >= v3.9 (arch/metag) >> --- >> v3 (James Hogan): >> - fix so that 64-bit parisc processes still use the 1GB limit. >> CONFIG_STACK_GROWSUP arches should provide a STACK_SIZE_MAX in their >> asm/processor.h, and for parisc it depends on USER_WIDE_MODE (whether >> the current process is 64-bit). >> v2 (James Hogan): >> - updated description to mention BUG on metag. >> - added custom range limit for METAG. >> - moved Kconfig symbol to mm/Kconfig and reworded. >> - fixed "matag" typo. >> --- >> arch/metag/include/asm/processor.h | 2 ++ >> arch/parisc/include/asm/processor.h | 5 +++++ >> arch/parisc/kernel/sys_parisc.c | 6 +++--- >> fs/exec.c | 6 +++--- >> mm/Kconfig | 15 +++++++++++++++ >> 5 files changed, 28 insertions(+), 6 deletions(-) >> >> diff --git a/arch/metag/include/asm/processor.h b/arch/metag/include/asm/processor.h >> index f16477d1f571..a8a37477c66e 100644 >> --- a/arch/metag/include/asm/processor.h >> +++ b/arch/metag/include/asm/processor.h >> @@ -22,6 +22,8 @@ >> /* Add an extra page of padding at the top of the stack for the guard page. */ >> #define STACK_TOP (TASK_SIZE - PAGE_SIZE) >> #define STACK_TOP_MAX STACK_TOP >> +/* Maximum virtual space for stack */ >> +#define STACK_SIZE_MAX (CONFIG_MAX_STACK_SIZE_MB*1024*1024) >> >> /* This decides where the kernel will search for a free chunk of vm >> * space during mmap's. >> diff --git a/arch/parisc/include/asm/processor.h b/arch/parisc/include/asm/processor.h >> index 198a86feb574..d951c9681ab3 100644 >> --- a/arch/parisc/include/asm/processor.h >> +++ b/arch/parisc/include/asm/processor.h >> @@ -55,6 +55,11 @@ >> #define STACK_TOP TASK_SIZE >> #define STACK_TOP_MAX DEFAULT_TASK_SIZE >> >> +/* Allow bigger stacks for 64-bit processes */ >> +#define STACK_SIZE_MAX (USER_WIDE_MODE \ >> + ? (1 << 30) /* 1 GB */ \ >> + : (CONFIG_MAX_STACK_SIZE_MB*1024*1024)) >> + >> #endif >> >> #ifndef __ASSEMBLY__ >> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c >> index 31ffa9b55322..e1ffea2f9a0b 100644 >> --- a/arch/parisc/kernel/sys_parisc.c >> +++ b/arch/parisc/kernel/sys_parisc.c >> @@ -72,10 +72,10 @@ static unsigned long mmap_upper_limit(void) >> { >> unsigned long stack_base; >> >> - /* Limit stack size to 1GB - see setup_arg_pages() in fs/exec.c */ >> + /* Limit stack size - see setup_arg_pages() in fs/exec.c */ >> stack_base = rlimit_max(RLIMIT_STACK); >> - if (stack_base > (1 << 30)) >> - stack_base = 1 << 30; >> + if (stack_base > STACK_SIZE_MAX) >> + stack_base = STACK_SIZE_MAX; >> >> return PAGE_ALIGN(STACK_TOP - stack_base); >> } >> diff --git a/fs/exec.c b/fs/exec.c >> index 476f3ebf437e..238b7aa26f68 100644 >> --- a/fs/exec.c >> +++ b/fs/exec.c >> @@ -657,10 +657,10 @@ int setup_arg_pages(struct linux_binprm *bprm, >> unsigned long rlim_stack; >> >> #ifdef CONFIG_STACK_GROWSUP >> - /* Limit stack size to 1GB */ >> + /* Limit stack size */ >> stack_base = rlimit_max(RLIMIT_STACK); >> - if (stack_base > (1 << 30)) >> - stack_base = 1 << 30; >> + if (stack_base > STACK_SIZE_MAX) >> + stack_base = STACK_SIZE_MAX; >> >> /* Make sure we didn't let the argument array grow too large. */ >> if (vma->vm_end - vma->vm_start > stack_base) >> diff --git a/mm/Kconfig b/mm/Kconfig >> index ebe5880c29d6..1b5a95f0fa01 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -581,3 +581,18 @@ config PGTABLE_MAPPING >> >> config GENERIC_EARLY_IOREMAP >> bool >> + >> +config MAX_STACK_SIZE_MB >> + int "Maximum user stack size for 32-bit processes (MB)" >> + default 80 >> + range 8 256 if METAG >> + range 8 2048 >> + depends on STACK_GROWSUP && (!64BIT || COMPAT) >> + help >> + This is the maximum stack size in Megabytes in the VM layout of 32-bit >> + 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. >> > From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Hogan Subject: Re: [PATCH] parisc,metag: Do not hardcode maximum userspace stack size Date: Tue, 13 May 2014 23:52:44 +0100 Message-ID: <5372A23C.702@imgtec.com> References: <20140430212602.GA20601@p100.fritz.box> <53622DBA.807@imgtec.com> <1398966636.2174.21.camel@dabdike> <5363876A.2030709@imgtec.com> <1399042116.2202.1.camel@dabdike> <5365EC05.5080900@gmx.de> <5371FF97.7030205@imgtec.com> <5372764A.2060906@gmx.de> Mime-Version: 1.0 Content-Transfer-Encoding: 7BIT Return-path: In-Reply-To: <5372764A.2060906@gmx.de> Sender: linux-parisc-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Helge Deller , James Bottomley Cc: linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, John David Anglin , linux-metag@vger.kernel.org Hi Helge, On 13/05/14 20:45, Helge Deller wrote: > On 05/13/2014 01:18 PM, James Hogan wrote: >> On 04/05/14 08:28, Helge Deller wrote: >>> 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. >> >> Sorry for the delay (I had most of last week off sick and still catching >> up). > > No problem. > >> That's a good point. It makes me think the best way to handle it is in a >> new definition in asm/processor.h, maybe STACK_SIZE_MAX. Does something >> like this look better? This patch isn't getting any cleaner >> unfortunately. > > > Yes, it's correct now. > Just tested it. Thanks! Thanks. > Another problem: > I think you wanted to get it backported into older kernels? Yeh, back to v3.9 ideally. > It seems the changes to mm/Kconfig will not apply cleanly to 3.14 or lower, Hmm, I guess the patch could be split easily though such that METAG always defined STACK_SIZE_MAX as 256MB and parisc always as 1GB (i.e. minimal fix for metag without actually changing any stack sizes), then have a second patch (not for stable) to make it match the v3 patch. I'll try that (I probably should have done that in the first place). Thanks James > and the changes to arch/parisc/kernel/sys_parisc.c will not apply to 3.13 or lower... > > Maybe cleaning up the patch to apply cleanly to 3.14 would make sense > and ignore older kernels? > > Helge > > >> From 6ecb0392a3b670c4bf1641a6ec56f22427ca8b57 Mon Sep 17 00:00:00 2001 >> From: Helge Deller >> Date: Wed, 30 Apr 2014 23:26:02 +0200 >> Subject: [PATCH 1/1] parisc,metag: Do not hardcode maximum userspace stack >> size >> >> This patch affects only architectures where the stack grows upwards >> (currently parisc and metag only). On those do not hardcode the maximum >> initial stack size to 1GB for 32-bit processes, but make it configurable >> via a config option. >> >> The main problem with the hardcoded stack size is, that we have two >> memory regions which grow upwards: stack and heap. To keep most of the >> memory available for heap in a flexmap memoy layout, it makes no sense >> to hard allocate up to 1GB of the memory for stack which can't be used >> as heap then. >> >> This patch makes the stack size configurable and uses 80MB as default >> value which has been in use during the last few years on parisc and >> which didn't showed any problems yet. >> >> This also fixes a BUG on metag if the RLIMIT_STACK hard limit is >> increased beyond a safe value by root. E.g. when starting a process >> after running "ulimit -H -s unlimited" it will then attempt to use a >> stack size of the maximum 1GB which is far too big for metag's limited >> user virtual address space (stack_top is usually 0x3ffff000): >> BUG: failure at fs/exec.c:589/shift_arg_pages()! >> >> Signed-off-by: Helge Deller >> Signed-off-by: James Hogan >> Cc: linux-parisc@vger.kernel.org >> Cc: linux-metag@vger.kernel.org >> Cc: John David Anglin >> Cc: stable@vger.kernel.org # only needed for >= v3.9 (arch/metag) >> --- >> v3 (James Hogan): >> - fix so that 64-bit parisc processes still use the 1GB limit. >> CONFIG_STACK_GROWSUP arches should provide a STACK_SIZE_MAX in their >> asm/processor.h, and for parisc it depends on USER_WIDE_MODE (whether >> the current process is 64-bit). >> v2 (James Hogan): >> - updated description to mention BUG on metag. >> - added custom range limit for METAG. >> - moved Kconfig symbol to mm/Kconfig and reworded. >> - fixed "matag" typo. >> --- >> arch/metag/include/asm/processor.h | 2 ++ >> arch/parisc/include/asm/processor.h | 5 +++++ >> arch/parisc/kernel/sys_parisc.c | 6 +++--- >> fs/exec.c | 6 +++--- >> mm/Kconfig | 15 +++++++++++++++ >> 5 files changed, 28 insertions(+), 6 deletions(-) >> >> diff --git a/arch/metag/include/asm/processor.h b/arch/metag/include/asm/processor.h >> index f16477d1f571..a8a37477c66e 100644 >> --- a/arch/metag/include/asm/processor.h >> +++ b/arch/metag/include/asm/processor.h >> @@ -22,6 +22,8 @@ >> /* Add an extra page of padding at the top of the stack for the guard page. */ >> #define STACK_TOP (TASK_SIZE - PAGE_SIZE) >> #define STACK_TOP_MAX STACK_TOP >> +/* Maximum virtual space for stack */ >> +#define STACK_SIZE_MAX (CONFIG_MAX_STACK_SIZE_MB*1024*1024) >> >> /* This decides where the kernel will search for a free chunk of vm >> * space during mmap's. >> diff --git a/arch/parisc/include/asm/processor.h b/arch/parisc/include/asm/processor.h >> index 198a86feb574..d951c9681ab3 100644 >> --- a/arch/parisc/include/asm/processor.h >> +++ b/arch/parisc/include/asm/processor.h >> @@ -55,6 +55,11 @@ >> #define STACK_TOP TASK_SIZE >> #define STACK_TOP_MAX DEFAULT_TASK_SIZE >> >> +/* Allow bigger stacks for 64-bit processes */ >> +#define STACK_SIZE_MAX (USER_WIDE_MODE \ >> + ? (1 << 30) /* 1 GB */ \ >> + : (CONFIG_MAX_STACK_SIZE_MB*1024*1024)) >> + >> #endif >> >> #ifndef __ASSEMBLY__ >> diff --git a/arch/parisc/kernel/sys_parisc.c b/arch/parisc/kernel/sys_parisc.c >> index 31ffa9b55322..e1ffea2f9a0b 100644 >> --- a/arch/parisc/kernel/sys_parisc.c >> +++ b/arch/parisc/kernel/sys_parisc.c >> @@ -72,10 +72,10 @@ static unsigned long mmap_upper_limit(void) >> { >> unsigned long stack_base; >> >> - /* Limit stack size to 1GB - see setup_arg_pages() in fs/exec.c */ >> + /* Limit stack size - see setup_arg_pages() in fs/exec.c */ >> stack_base = rlimit_max(RLIMIT_STACK); >> - if (stack_base > (1 << 30)) >> - stack_base = 1 << 30; >> + if (stack_base > STACK_SIZE_MAX) >> + stack_base = STACK_SIZE_MAX; >> >> return PAGE_ALIGN(STACK_TOP - stack_base); >> } >> diff --git a/fs/exec.c b/fs/exec.c >> index 476f3ebf437e..238b7aa26f68 100644 >> --- a/fs/exec.c >> +++ b/fs/exec.c >> @@ -657,10 +657,10 @@ int setup_arg_pages(struct linux_binprm *bprm, >> unsigned long rlim_stack; >> >> #ifdef CONFIG_STACK_GROWSUP >> - /* Limit stack size to 1GB */ >> + /* Limit stack size */ >> stack_base = rlimit_max(RLIMIT_STACK); >> - if (stack_base > (1 << 30)) >> - stack_base = 1 << 30; >> + if (stack_base > STACK_SIZE_MAX) >> + stack_base = STACK_SIZE_MAX; >> >> /* Make sure we didn't let the argument array grow too large. */ >> if (vma->vm_end - vma->vm_start > stack_base) >> diff --git a/mm/Kconfig b/mm/Kconfig >> index ebe5880c29d6..1b5a95f0fa01 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -581,3 +581,18 @@ config PGTABLE_MAPPING >> >> config GENERIC_EARLY_IOREMAP >> bool >> + >> +config MAX_STACK_SIZE_MB >> + int "Maximum user stack size for 32-bit processes (MB)" >> + default 80 >> + range 8 256 if METAG >> + range 8 2048 >> + depends on STACK_GROWSUP && (!64BIT || COMPAT) >> + help >> + This is the maximum stack size in Megabytes in the VM layout of 32-bit >> + 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. >> >