On 28.04.25 21:37, Lorenzo Stoakes wrote:
On Mon, Apr 28, 2025 at 07:23:18PM +0200, David Hildenbrand wrote:
On 28.04.25 18:24, Peter Xu wrote:
On Mon, Apr 28, 2025 at 06:16:21PM +0200, David Hildenbrand wrote:
Probably due to what config you have. E.g., when I'm looking mine it's
much bigger and already consuming 256B, but it's because I enabled more
things (userfaultfd, lockdep, etc.).
Note that I enabled everything that you would expect on a production system
(incld. userfaultfd, mempolicy, per-vma locks), so I didn't enable lockep.
I still doubt whether you at least enabled userfaultfd, e.g., your previous
paste has:
struct vm_userfaultfd_ctx vm_userfaultfd_ctx; /* 176 0 */
Not something that matters.. but just in case you didn't use the expected
config file you wanted to use..
You're absolutely right. I only briefly rechecked for this purpose here on
my notebook, and only looked for the existence of members, not expecting
that we have confusing stuff like vm_userfaultfd_ctx.
I checked again and the size stays at 192 with allyesconfig and then
disabling debug options.
I think a reasonable case is everything on, except CONFIG_DEBUG_LOCK_ALLOC and I
don't care about nommu.
So:
CONFIG_PER_VMA_LOCK
CONFIG_SWAP
CONFIG_MMU (exclude the nommu vm_region field)
CONFIG_NUMA
CONFIG_NUMA_BALANCING
CONFIG_PER_VMA_LOCK
CONFIG_ANON_VMA_NAME
__HAVE_PFNMAP_TRACKING
Yes.
And our ugly friend CONFIG_USERFAULTFD
that is
struct vm_userfaultfd_ctx {
struct userfaultfd_ctx *ctx;
};
#else /* CONFIG_USERFAULTFD */
#define NULL_VM_UFFD_CTX ((struct vm_userfaultfd_ctx) {})
struct vm_userfaultfd_ctx {};
#endif /* CONFIG_USERFAULTFD */
(yes, you made the same mistake as I made when skimming if everything
relevant was enabled)
So to be clear - allyesconfig w/o debug gives us this yes? And we don't add a
cache line? In which case all good :)
Looks like it!
--
Cheers,
David / dhildenb
