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Peter Anvin" , Ingo Molnar , James Bottomley , "Kirill A. Shutemov" , Mark Rutland , Mike Rapoport , Michael Kerrisk , Palmer Dabbelt , Paul Walmsley , Peter Zijlstra , Rick Edgecombe , Roman Gushchin , Shakeel Butt , Shuah Khan , Thomas Gleixner , Tycho Andersen , Will Deacon , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-nvdimm@lists.01.org, linux-riscv@lists.infradead.org, x86@kernel.org, Hagen Paul Pfeifer X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit On Thu, Dec 03, 2020 at 08:29:44AM +0200, Mike Rapoport wrote: > +static vm_fault_t secretmem_fault(struct vm_fault *vmf) > +{ > + struct address_space *mapping = vmf->vma->vm_file->f_mapping; > + struct inode *inode = file_inode(vmf->vma->vm_file); > + pgoff_t offset = vmf->pgoff; > + vm_fault_t ret = 0; > + unsigned long addr; > + struct page *page; > + int err; > + > + if (((loff_t)vmf->pgoff << PAGE_SHIFT) >= i_size_read(inode)) > + return vmf_error(-EINVAL); > + > + page = find_get_page(mapping, offset); > + if (!page) { > + > + page = secretmem_alloc_page(vmf->gfp_mask); > + if (!page) > + return vmf_error(-ENOMEM); Just use VM_FAULT_OOM directly. > + err = add_to_page_cache(page, mapping, offset, vmf->gfp_mask); > + if (unlikely(err)) > + goto err_put_page; What if the error is EEXIST because somebody else raced with you to add a new page to the page cache? > + err = set_direct_map_invalid_noflush(page, 1); > + if (err) > + goto err_del_page_cache; Does this work correctly if somebody else has a reference to the page in the meantime? > + addr = (unsigned long)page_address(page); > + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); > + > + __SetPageUptodate(page); Once you've added it to the cache, somebody else can come along and try to lock it. They will set PageWaiter. Now you call __SetPageUptodate and wipe out their PageWaiter bit. So you won't wake them up when you unlock. You can call __SetPageUptodate before adding it to the page cache, but once it's visible to another thread, you can't do that. > + ret = VM_FAULT_LOCKED; > + } > + > + vmf->page = page; You're supposed to return the page locked, so use find_lock_page() instead of find_get_page(). > + return ret; > + > +err_del_page_cache: > + delete_from_page_cache(page); > +err_put_page: > + put_page(page); > + return vmf_error(err); > +} _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org