On Tue, Nov 05, 2019 at 12:26:58AM +0200, Jarkko Sakkinen wrote: > On Mon, Nov 04, 2019 at 12:46:02PM -0800, Sean Christopherson wrote: > > On Mon, Nov 04, 2019 at 10:01:39PM +0200, Jarkko Sakkinen wrote: > > > The reasoning is the same as in > > > > > > http://git.infradead.org/users/jjs/linux-tpmdd.git/commit/abd55954f91a3aacc1d260d2411cf776ec4d5fd2 > > > > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx> > > > --- > > > arch/x86/kernel/cpu/sgx/ioctl.c | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c > > > index 5b28a9c0cb68..d53aee5a64c1 100644 > > > --- a/arch/x86/kernel/cpu/sgx/ioctl.c > > > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c > > > @@ -259,7 +259,7 @@ static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg) > > > if (copy_from_user(&ecreate, arg, sizeof(ecreate))) > > > return -EFAULT; > > > > > > - secs_page = alloc_page(GFP_HIGHUSER); > > > + secs_page = alloc_page(GFP_KERNEL); > > > if (!secs_page) > > > return -ENOMEM; > > > > > > @@ -674,7 +674,7 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > > > if (copy_from_user(&einit, arg, sizeof(einit))) > > > return -EFAULT; > > > > > > - initp_page = alloc_page(GFP_HIGHUSER); > > > + initp_page = alloc_page(GFP_KERNEL); > > > > Would it make sense to use GFP_KERNEL_ACCOUNT? The accounting would be > > weird for the case where userspace is using a builder process, but even in > > that case it's not flat out wrong to account per-enclave memory allocations. > > I did not find a single call site that would use that for allocating > memory for function-internal data. Actually, the fact that the allocations are transient is an even better argument for accounting the memory, as the weirdness I was referring to doesn't exist for the builder concept. But looking more closely, Documentation/core-api/memory-allocation.rst states: * Untrusted allocations triggered from userspace should be a subject of kmem accounting and must have ``__GFP_ACCOUNT`` bit set. There is the handy ``GFP_KERNEL_ACCOUNT`` shortcut for ``GFP_KERNEL`` allocations that should be accounted. That means all uses of GFP_KERNEL except in sgx_alloc_epc_section() should be converted to GFP_KERNEL_ACCOUNTED. As is, depending on fd limits[*], a single process can easily burn through multiple GBs of memory simply by opening /dev/sgx/enclave in a loop. [*] AFAICT, systemd is upping the max number of open files to 1M on my systems. I don't _think_ I changed a setting anywhere?
