On Wed, 4 Apr 2018, Laurent Dufour wrote: > > I also think the following is needed: > > > > diff --git a/fs/exec.c b/fs/exec.c > > --- a/fs/exec.c > > +++ b/fs/exec.c > > @@ -312,6 +312,10 @@ static int __bprm_mm_init(struct linux_binprm *bprm) > > vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP; > > vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); > > INIT_LIST_HEAD(&vma->anon_vma_chain); > > +#ifdef CONFIG_SPECULATIVE_PAGE_FAULT > > + seqcount_init(&vma->vm_sequence); > > + atomic_set(&vma->vm_ref_count, 0); > > +#endif > > > > err = insert_vm_struct(mm, vma); > > if (err) > > No, this not needed because the vma is allocated with kmem_cache_zalloc() so > vm_ref_count is 0, and insert_vm_struc() will later call > __vma_link_rb() which will call seqcount_init(). > > Furhtermore, in case of error, the vma structure is freed without calling > get_vma() so there is risk of lockdep warning. > Perhaps you're working from a different tree than I am, or you fixed the lockdep warning differently when adding to dup_mmap() and mmap_region(). I got the following two lockdep errors. I fixed it locally by doing the seqcount_init() and atomic_set() everywhere a vma could be initialized. INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 12 PID: 1 Comm: init Not tainted Call Trace: [<ffffffff8b12026f>] dump_stack+0x67/0x98 [<ffffffff8a92b616>] register_lock_class+0x1e6/0x4e0 [<ffffffff8a92cfe9>] __lock_acquire+0xb9/0x1710 [<ffffffff8a92ef3a>] lock_acquire+0xba/0x200 [<ffffffff8aa827df>] mprotect_fixup+0x10f/0x310 [<ffffffff8aade3fd>] setup_arg_pages+0x12d/0x230 [<ffffffff8ab4564a>] load_elf_binary+0x44a/0x1740 [<ffffffff8aadde9b>] search_binary_handler+0x9b/0x1e0 [<ffffffff8ab44e96>] load_script+0x206/0x270 [<ffffffff8aadde9b>] search_binary_handler+0x9b/0x1e0 [<ffffffff8aae0355>] do_execveat_common.isra.32+0x6b5/0x9d0 [<ffffffff8aae069c>] do_execve+0x2c/0x30 [<ffffffff8a80047b>] run_init_process+0x2b/0x30 [<ffffffff8b1358d4>] kernel_init+0x54/0x110 [<ffffffff8b2001ca>] ret_from_fork+0x3a/0x50 and INFO: trying to register non-static key. the code is fine but needs lockdep annotation. turning off the locking correctness validator. CPU: 21 PID: 1926 Comm: mkdir Not tainted Call Trace: [<ffffffff985202af>] dump_stack+0x67/0x98 [<ffffffff97d2b616>] register_lock_class+0x1e6/0x4e0 [<ffffffff97d2cfe9>] __lock_acquire+0xb9/0x1710 [<ffffffff97d2ef3a>] lock_acquire+0xba/0x200 [<ffffffff97e73c09>] unmap_page_range+0x89/0xaa0 [<ffffffff97e746af>] unmap_single_vma+0x8f/0x100 [<ffffffff97e74a1b>] unmap_vmas+0x4b/0x90 [<ffffffff97e7f833>] exit_mmap+0xa3/0x1c0 [<ffffffff97cc1b23>] mmput+0x73/0x120 [<ffffffff97ccbacd>] do_exit+0x2bd/0xd60 [<ffffffff97ccc5b7>] SyS_exit+0x17/0x20 [<ffffffff97c01f1d>] do_syscall_64+0x6d/0x1a0 [<ffffffff9860005a>] entry_SYSCALL_64_after_hwframe+0x26/0x9b I think it would just be better to generalize vma allocation to initialize certain fields and init both spf fields properly for CONFIG_SPECULATIVE_PAGE_FAULT. It's obviously too delicate as is.
