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Peter Anvin" , , , , , , References: <20230821123056.2109942-1-wangkefeng.wang@huawei.com> <20230821123056.2109942-5-wangkefeng.wang@huawei.com> <20230824083225.10112-A-hca@linux.ibm.com> From: Kefeng Wang In-Reply-To: <20230824083225.10112-A-hca@linux.ibm.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm100001.china.huawei.com (7.185.36.93) X-CFilter-Loop: Reflected X-Rspamd-Queue-Id: 2291B40002 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: ptzncy4wdzg4s4bc3dmkomj1stkc48s3 X-HE-Tag: 1693012025-491279 X-HE-Meta: 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 7lJuwQBB vy2uWSeEg6Fu8p0yvvldmHWqM2/QqfE1P/vZTYyqn7ZjPSaF+Eq/+DxbSxzIM/YPpSI6L26YvnVTGOcO4aqI/6Nc0x5jmNlHdLj1wjAOYrkQlcf9aD2Hsb4AxWP5GnIrxDQQN8z/4szv2B9mImrWqKyFAFOjSxvgZLKz022WtPxXMjctmZlpC+rdYYr8GDPTEFcG+uqR4RCx9Xz0ya0xkF3nRimEpgGq+A1sOHMDoKQoTloU= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/8/24 16:32, Heiko Carstens wrote: > On Thu, Aug 24, 2023 at 10:16:33AM +0200, Alexander Gordeev wrote: >> On Mon, Aug 21, 2023 at 08:30:50PM +0800, Kefeng Wang wrote: >>> Use new try_vma_locked_page_fault() helper to simplify code. >>> No functional change intended. >>> >>> Signed-off-by: Kefeng Wang >>> --- >>> arch/s390/mm/fault.c | 66 ++++++++++++++++++-------------------------- >>> 1 file changed, 27 insertions(+), 39 deletions(-) > ... >>> - fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); >>> - if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) >>> - vma_end_read(vma); >>> - if (!(fault & VM_FAULT_RETRY)) { >>> - count_vm_vma_lock_event(VMA_LOCK_SUCCESS); >>> - if (likely(!(fault & VM_FAULT_ERROR))) >>> - fault = 0; >> >> This fault fixup is removed in the new version. > ... > >>> + vmf.vm_flags = VM_WRITE; >>> + if (vmf.vm_flags == VM_WRITE) >>> + vmf.flags |= FAULT_FLAG_WRITE; >>> + >>> + fault = try_vma_locked_page_fault(&vmf); >>> + if (fault == VM_FAULT_NONE) >>> + goto lock_mm; >> >> Because VM_FAULT_NONE is set to 0 it gets confused with >> the success code of 0 returned by a fault handler. In the >> former case we want to continue, while in the latter - >> successfully return. I think it applies to all archs. > ... >> FWIW, this series ends up with kernel BUG at arch/s390/mm/fault.c:341! > I didn't test and only built, this is a RFC to want to know whether the way to add three more numbers into vmf and using vmf in arch's page fault is feasible or not. > Without having looked in detail into this patch: all of this is likely > because s390's fault handling is quite odd. Not only because fault is set > to 0, but also because of the private VM_FAULT values like > VM_FAULT_BADCONTEXT. I'm just cleaning up all of this, but it won't make it > for the next merge window. Sure, if re-post, will drop the s390's change, but as mentioned above, the abstract of the generic vma locked and changes may be not perfect, let's wait for more response. Thanks all. > > Therefore I'd like to ask to drop the s390 conversion of this series, and > if this series is supposed to be merged the s390 conversion needs to be > done later. Let's not waste more time on the current implementation, > please.