Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932219AbXBOF01 (ORCPT ); Thu, 15 Feb 2007 00:26:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932221AbXBOF01 (ORCPT ); Thu, 15 Feb 2007 00:26:27 -0500 Received: from mga09.intel.com ([134.134.136.24]:38803 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932219AbXBOF00 convert rfc822-to-8bit (ORCPT ); Thu, 15 Feb 2007 00:26:26 -0500 X-ExtLoop1: 1 X-IronPort-AV: i="4.14,173,1170662400"; d="scan'208"; a="46696573:sNHT28753803" X-MimeOLE: Produced By Microsoft Exchange V6.5 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Subject: RE: [PATCH] aio: fix kernel bug when page is temporally busy Date: Thu, 15 Feb 2007 08:26:05 +0300 Message-ID: In-Reply-To: <20070214193051.4b008d61.akpm@linux-foundation.org> X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [PATCH] aio: fix kernel bug when page is temporally busy Thread-Index: AcdQseVn7HFoadpiSjiHzR3MKAaoswABQ+Wg From: "Ananiev, Leonid I" To: "Andrew Morton" Cc: X-OriginalArrivalTime: 15 Feb 2007 05:26:22.0554 (UTC) FILETIME=[D4635BA0:01C750C1] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6322 Lines: 152 > Please, tell us what problem this is fixing so that we can look into > alternative solutions. This patch fixes a kernel panic "Kernel BUG at fs/aio.c:509" http://marc.theaimsgroup.com/?l=linux-kernel&m=117031052517746&w=2 First of all it was found that the kernel panic happens after IO error reporting. But later it was found that the actual reason is not in real IO error but in a busy page. EIO is returned if page has unstable state while IO completion result is processing. If aio_run_iocb() as well as in do_sync_read/write() get EIO result it is considered as IO is finished and IO control block could be free; result is reported to caller. I suppose that aio_run_iocb() as well as in do_sync_read/write() should have a chance to differ real EIO and EIO which is actually means EAGAYN. That functions test for EIOCBRETRY meaning EAGAYN purpose. do_sync_read/write() retries IO as well as aio: for (;;) { ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos); if (ret != -EIOCBRETRY) break; wait_on_retry_sync_kiocb(&kiocb); } By the way EIOCBRETRY is never actually set in the kernel. So what is the purpose of previous lines? More details about EIO returning: aio_complete: res=-5 iocb=ffff81002b38f080 ki_users=2 [] invalidate_inode_pages2_range+0x236/0x26b [] ext3_direct_IO+0x16c/0x19e [] ext3_get_block+0x0/0xe2 [] generic_file_direct_IO+0xb9/0xcf [] generic_file_direct_write+0x67/0x10e [] __generic_file_aio_write_nolock+0x2d6/0x3fe [] __switch_to+0x26f/0x27e [] thread_return+0x0/0xd8 [] generic_file_aio_write+0x67/0xc7 [] ext3_file_write+0x0/0x8f [] ext3_file_write+0x16/0x8f [] ext3_file_write+0x0/0x8f [] aio_rw_vect_retry+0x72/0x14f [] aio_run_iocb+0xe6/0x187 [] io_submit_one+0x296/0x2e3 [] sys_io_submit+0x9b/0x108 [] default_wake_function+0x0/0xe [] system_call+0x7e/0x83 Call Trace: [] aio_complete+0x5c/0x18c [] finished_one_bio+0xac/0xf3 [] dio_bio_complete+0x95/0xaa [] dio_bio_end_aio+0x20/0x25 [] __end_that_request_first+0x10e/0x3fd [] scsi_end_request+0x27/0xc9 [] scsi_io_completion+0xf0/0x2c5 [] ahd_done+0x537/0x580 [] sd_rw_intr+0x182/0x1ad [] blk_done_softirq+0x5c/0x6a [] __do_softirq+0x55/0xc3 [] ack_apic_level+0x37/0x4b [] call_softirq+0x1c/0x28 [] do_softirq+0x2c/0x7d [] do_IRQ+0xa8/0xc8 [] mwait_idle+0x0/0x20 [] ret_from_intr+0x0/0xa [] mwait_idle_with_hints+0x44/0x45 [] mwait_idle+0xc/0x20 [] cpu_idle+0x8b/0xb0 [] start_secondary+0x462/0x471 -----Original Message----- From: Andrew Morton [mailto:akpm@linux-foundation.org] Sent: Thursday, February 15, 2007 6:31 AM To: Ananiev, Leonid I Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] aio: fix kernel bug when page is temporally busy On Wed, 14 Feb 2007 20:51:33 +0300 "Ananiev, Leonid I" wrote: > Fix kernel bug when IO page is temporally busy: > invalidate_inode_pages2_range() returns EIOCBRETRY but not EIO. > invalidate_inode_pages2() returns EIO as earlier. > > Signed-off-by: Leonid Ananiev > --- > --- linux-2.6.20/mm/truncate.c 2007-02-04 10:44:54.000000000 -0800 > +++ linux-2.6.20p/mm/truncate.c 2007-02-08 22:56:52.000000000 -0800 > @@ -366,7 +366,7 @@ static int do_launder_page(struct addres > * Any pages which are found to be mapped into pagetables are unmapped prior to > * invalidation. > * > - * Returns -EIO if any pages could not be invalidated. > + * Returns -EIOCBRETRY if any pages could not be invalidated. > */ > int invalidate_inode_pages2_range(struct address_space *mapping, > pgoff_t start, pgoff_t end) > @@ -423,7 +423,7 @@ int invalidate_inode_pages2_range(struct > } > ret = do_launder_page(mapping, page); > if (ret == 0 && !invalidate_complete_page2(mapping, page)) > - ret = -EIO; > + ret = -EIOCBRETRY; > unlock_page(page); > } > pagevec_release(&pvec); > @@ -444,6 +444,7 @@ EXPORT_SYMBOL_GPL(invalidate_inode_pages > */ > int invalidate_inode_pages2(struct address_space *mapping) > { > - return invalidate_inode_pages2_range(mapping, 0, -1); > + int ret = invalidate_inode_pages2_range(mapping, 0, -1); > + return (ret < 0)?-EIO:ret; > } > EXPORT_SYMBOL_GPL(invalidate_inode_pages2); If someone later uses invalidate_inode_pages2_range() elsewhere, they're going to need to know to convert -EIOCBRETRY into -EIO, if they weren't called by aio. Or something. Please, tell us what problem this is fixing so that we can look into alternative solutions. For example, one acceptable-but-ugly solution might be to do: static inline int invalidate_inode_pages2_range(struct address_space *mapping, pgoff_t start, pgoff_t end) { return __invalidate_inode_pages2_range(mapping, start, end, 0); } static inline int invalidate_inode_pages2_range_for_aio(struct address_space *mapping, pgoff_t start, pgoff_t end) { return __invalidate_inode_pages2_range(mapping, start, end, 1); } and to then use invalidate_inode_pages2_range_for_aio() from the appropriate callsite. But without a complete description of the bug which this is fixing, it's hard to say how practical such an approach would be. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/