On Mon, Apr 15, 2024 at 11:18 AM Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
>
> On Mon, Apr 15, 2024 at 09:14:10AM -0700, Suren Baghdasaryan wrote:
> > > if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
> > > - vma_end_read(vma);
> > > - return VM_FAULT_RETRY;
> > > + if (!mmap_read_trylock(vma->vm_mm)) {
> > > + vma_end_read(vma);
> > > + return VM_FAULT_RETRY;
> > > + }
> > > }
> > > if (__anon_vma_prepare(vma))
> > > return VM_FAULT_OOM;
> >
> > You should drop mmap_lock when returning VM_FAULT_OOM as well.
> >
> > > + if (vmf->flags & FAULT_FLAG_VMA_LOCK)
> > > + mmap_read_unlock(vma->vm_mm);
> > > return 0;
> > > }
>
> Thanks. Fixed and pushed to
> git://git.infradead.org/users/willy/pagecache.git vma-lock
That looks correct now.
Reviewed-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
>
> +++ b/mm/memory.c
> @@ -3224,16 +3224,21 @@ static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf)
> vm_fault_t vmf_anon_prepare(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> + vm_fault_t ret = 0;
>
> if (likely(vma->anon_vma))
> return 0;
> if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
> - vma_end_read(vma);
> - return VM_FAULT_RETRY;
> + if (!mmap_read_trylock(vma->vm_mm)) {
> + vma_end_read(vma);
> + return VM_FAULT_RETRY;
> + }
> }
> if (__anon_vma_prepare(vma))
> - return VM_FAULT_OOM;
> - return 0;
> + ret = VM_FAULT_OOM;
> + if (vmf->flags & FAULT_FLAG_VMA_LOCK)
> + mmap_read_unlock(vma->vm_mm);
> + return ret;
> }
>
> /*
>
