Messages in this thread | | | From | KOSAKI Motohiro <> | Subject | Re: 2.6.33-rc8 breaks UML with Restrict initial stack space expansion to rlimit | Date | Mon, 15 Feb 2010 15:59:26 +0900 (JST) |
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> > > In message <20100214164023.GA2726@jm.kir.nu> you wrote: > > It looks like the commit 803bf5ec259941936262d10ecc84511b76a20921 > > (fs/exec.c: restrict initial stack space expansion to rlimit) broke my > > user mode Linux setup by somehow preventing system setup from running > > properly (or killing some processes that try to mount things, etc.). > > This commit turned up as the reason based on git bisect and reverting it > > fixes my UML test setup (Ubuntu 9.10 on both host and in UML and AMD64 > > arch for both). I have no idea what exactly would be the main cause for > > this issue, but this looks like a somewhat unfortunately timed > > regression in 2.6.33-rc8. > > > > The failed run shows like this (with current linux-2.6.git): > > > > ... > > EXT3-fs (ubda): mounted filesystem with writeback data mode > > VFS: Mounted root (ext3 filesystem) readonly on device 98:0. > > IRQ 3/console-write: IRQF_DISABLED is not guaranteed on shared IRQs > > IRQ 2/console: IRQF_DISABLED is not guaranteed on shared IRQs > > IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs > > IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs > > mountall: mount /sys/kernel/debug [218] killed by KILL signal > > mountall: Filesystem could not be mounted: /sys/kernel/debug > > mountall: mount /dev [219] killed by KILL signal > > mountall: Filesystem could not be mounted: /dev > > mountall: mount /tmp [220] killed by KILL signal > > mountall: Filesystem could not be mounted: /tmp > > mountall: mount /var/lock [222] killed by KILL signal > > mountall: Filesystem could not be mounted: /var/lock > > ... > > > > > > With 803bf5ec reverted, UML comes up and the output looks like this: > > > > ... > > EXT3-fs (ubda): mounted filesystem with writeback data mode > > VFS: Mounted root (ext3 filesystem) readonly on device 98:0. > > IRQ 3/console-write: IRQF_DISABLED is not guaranteed on shared IRQs > > IRQ 2/console: IRQF_DISABLED is not guaranteed on shared IRQs > > IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs > > IRQ 10/winch: IRQF_DISABLED is not guaranteed on shared IRQs > > init: procps main process (226) terminated with status 255 > > fsck from util-linux-ng 2.16 > > ... > > Jouni, > > I can reproduce this now. > > We got the logic wrong in one of the cleanups and hence we aren't > actually changing the stack reservation ever, when we intended on > allocating up to 20 new pages. > > The: > rlim_stack = min(rlim_stack, stack_size); > always chooses stack_size hence we end up not changing the stack at all. > This seems to cause fatal problems on UML, but is obviously not what was > intended for archs as well. > > The following works for me on PPC64 64k and 4k pages and UML on x86_64. > > Let me know if it fixes it for you also. > > Mikey > > > exec/fs: fix initial stack reservation > > 803bf5ec259941936262d10ecc84511b76a20921 (fs/exec.c: restrict initial > stack space expansion to rlimit) attempts to limit the initial stack to > 20*PAGE_SIZE. Unfortunately, in also attempting ensure the stack is not > reduced in size, we ended up not changing the stack at all. > > This caused a regression in UML resulting in most guest processes to be > killed. > > Signed-off-by: Michael Neuling <mikey@neuling.org> > cc: <stable@kernel.org> > > diff --git a/fs/exec.c b/fs/exec.c > index e95c692..e0e7b3c 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -637,15 +637,16 @@ int setup_arg_pages(struct linux_binprm *bprm, > * will align it up. > */ > rlim_stack = rlimit(RLIMIT_STACK) & PAGE_MASK; > - rlim_stack = min(rlim_stack, stack_size); > #ifdef CONFIG_STACK_GROWSUP > if (stack_size + stack_expand > rlim_stack) > - stack_base = vma->vm_start + rlim_stack; > + /* Expand only to rlimit, making sure not to shrink it */ > + stack_base = vma->vm_start + max(rlim_stack,stack_size); > else > stack_base = vma->vm_end + stack_expand; > #else > if (stack_size + stack_expand > rlim_stack) > - stack_base = vma->vm_end - rlim_stack; > + /* Expand only to rlimit, making sure not to shrink it */ > + stack_base = vma->vm_end - max(rlim_stack,stack_size); > else > stack_base = vma->vm_start - stack_expand; > #endif
- rlim_stack = min(rlim_stack, stack_size); + /* Expand only to rlimit, making sure not to shrink it */ + rlim_stack = max(rlim_stack, stack_size);
is better fix?
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