On Thu, Apr 13, 2017 at 4:13 PM, Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> wrote: > > > On 04/13/2017 03:16 PM, Anna Schumaker wrote: >> >> >> On 04/13/2017 03:07 PM, Olga Kornievskaia wrote: >>> On Thu, Apr 13, 2017 at 2:51 PM, Trond Myklebust >>> <trondmy@xxxxxxxxxxxxxxx> wrote: >>>> On Thu, 2017-04-13 at 14:00 -0400, Olga Kornievskaia wrote: >>>>> Hi folks, >>>>> >>>>> Looking for suggestions on how to fix a kernel oops. >>>>> >>>>> It's possible that there is a ctrl-c when the COMMIT is send. In case >>>>> of the COPY, it calls >>>>> nfs_commit_file() which calls wait_on_commit() that is interrupted by >>>>> the crtl-c and frees the nfs_page request. So when asynchronous >>>>> COMMIT >>>>> rpc comes back it tried to use the nfs_page request and gets the >>>>> oops. >>>>> >>>> >>>> Is that call to nfs_free_request() in nfs_commit_file() correct? >>> >>> yes, nfs_commit_file() creates a new request via nfs_create_request() >>> and in the end if calls nfs_free_request(); >>> >>>> It looks to me as if the same request will be freed in >>>> nfs_commit_release_pages(). >>> >>> so nfs_commit_release_pages() thru the >>> nfs_unlock_and_release_request() is going to call >>> nfs_release_request() from req->wb_kref.. I'm not sure if this is >>> setup(?) for the copy commit path? >>> >>> Otherwise, it would have seem that we'd be doing a double free and I >>> haven't seen that in testing (not that it can't be true)... >> >> I haven't seen any double-free messages during my testing either, so I thought it was okay. It's possible I'm wrong, though. I wonder if this is something that memory poisoning can help figure out? > > After some experimenting, I can still use the nfs_page after nfs_commit_inode() has returned withotu any memory issues. I think perhaps nfs_commit_file() needs to call nfs_release_request() instead of directly calling nfs_free_request(). nfs_release_request does a put on wb_kref and once it's 0 it'll call release. So I think with that change my ctrl-c no longer produces the oops either. I'll test a bit more and I'll send another patch. > >> >> Anna >> >>> >>> >>> >>>> >>>> Anna? >>>> >>>> -- >>>> Trond Myklebust >>>> Linux NFS client maintainer, PrimaryData >>>> trond.myklebust@xxxxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
