On Thu, Mar 20, 2014 at 5:30 AM, Thomas Gleixner <t...@linutronix.de> wrote: > On Thu, 20 Mar 2014, Stefani Seibold wrote: >> Am Donnerstag, den 20.03.2014, 10:53 +0100 schrieb Thomas Gleixner: >> > On Thu, 20 Mar 2014, Stefani Seibold wrote: >> > >> > > This patch add a correct out of memory handling for setup a 32 bit vDSO. >> > > >> > > The patch is against tip commit 4e40112c4ff6a577dd06d92b2a54cdf06265bf74 >> > > >> > > Signed-off-by: Stefani Seibold <stef...@seibold.net> >> > > --- >> > > arch/x86/vdso/vdso32-setup.c | 17 ++++++++++++++++- >> > > 1 file changed, 16 insertions(+), 1 deletion(-) >> > > >> > > diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c >> > > index 0bc363a..e1171c2 100644 >> > > --- a/arch/x86/vdso/vdso32-setup.c >> > > +++ b/arch/x86/vdso/vdso32-setup.c >> > > @@ -134,8 +134,14 @@ int __init sysenter_setup(void) >> > > } >> > > >> > > vdso32_size = (vdso_len + PAGE_SIZE - 1) / PAGE_SIZE; >> > > - vdso32_pages = kmalloc(sizeof(*vdso32_pages) * vdso32_size, >> > > GFP_ATOMIC); >> > > + >> > > + vdso32_pages = kmalloc(sizeof(*vdso32_pages) * vdso32_size, >> > > GFP_ATOMIC); >> > >> > Why is this GFP_ATOMIC and not GFP_ATOMIC ? >> > >> > That code is called either from identify_boot_cpu(), where GFP_KERNEL >> > is perfectly valid and from subsys_initcall(sysenter_setup) which is >> > way late in the boot process where GFP_KERNEL is the RightThing. >> > >> > Aside of that, why do we need to call it early for X86_32 and late for >> > X86_64? >> > >> > We need the vdso before we head off to user space, but not in the >> > early boot process. >> > >> >> All complains are design decisions not made by me. I will send a patch >> for the GFP_ATOMIC thing. For the other one it would be the best to ask >> Andy for the reason. > > I'm not saying it's your fault, but if we rework code, then we really > should question such things. What happens if you remove the x32 call > and make the x64 subsys thing valid for both cases? >
It's not just that. The x86_64 and x32 vdso page arrays are *far* cleaner than the 32-bit variant. They manage to do the entire vdso setup dance without any allocation at all. This avoids silly questions about error handling and GFP_KERNEL :) See vdso/vdso.S for the rather small amount of magic needed. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
