From owner-freebsd-current@FreeBSD.ORG Tue May 9 15:26:43 2006 Return-Path: X-Original-To: freebsd-current@FreeBSD.org Delivered-To: freebsd-current@FreeBSD.org Received: from green.homeunix.org (freefall.freebsd.org [216.136.204.21]) by hub.freebsd.org (Postfix) with ESMTP id 6744A16A5F1; Tue, 9 May 2006 15:26:43 +0000 (UTC) (envelope-from green@green.homeunix.org) Received: from green.homeunix.org (green@localhost [127.0.0.1]) by green.homeunix.org (8.13.4/8.13.1) with ESMTP id k49FQg3I053445; Tue, 9 May 2006 11:26:42 -0400 (EDT) (envelope-from green@green.homeunix.org) Received: (from green@localhost) by green.homeunix.org (8.13.4/8.13.1/Submit) id k49FQgwf053444; Tue, 9 May 2006 11:26:42 -0400 (EDT) (envelope-from green) Date: Tue, 9 May 2006 11:26:42 -0400 From: Brian Fundakowski Feldman To: Pawel Jakub Dawidek Message-ID: <20060509152641.GC1036@green.homeunix.org> References: <20060509140312.GA93453@garage.freebsd.pl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060509140312.GA93453@garage.freebsd.pl> User-Agent: Mutt/1.5.11 Cc: freebsd-current@FreeBSD.org, scottl@FreeBSD.org Subject: Re: contigmalloc(9) doesn't honour M_NOWAIT. X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 09 May 2006 15:26:43 -0000 On Tue, May 09, 2006 at 04:03:12PM +0200, Pawel Jakub Dawidek wrote: > Hi. > > Using a USB pendrive can lead to kernel panic because of the issue > mentioned in the subject. > > Trying sleep, but thread marked as sleeping prohibited > KDB: stack backtrace: > kdb_backtrace(c0602d36,1,c0602cb2,112,2) at kdb_backtrace+0x2e > sleepq_add(d7e13af0,c064c0e8,c060f7fd,0,0) at sleepq_add+0xba > msleep(d7e13af0,c064c0e8,44,c060f7fd,0) at msleep+0x209 > bwait(d7e13af0,44,c060f7fd,50a,0) at bwait+0x60 > swap_pager_putpages(c701ed98,e3c3ba44,1,1,e3c3ba00) at swap_pager_putpages+0x497 > vm_pageout_flush(e3c3ba44,1,1,61,3db) at vm_pageout_flush+0x172 > vm_contig_launder_page(c1ccbdb8,0,0,1ff,ffffffff) at vm_contig_launder_page+0x29b > vm_page_alloc_contig(4,0,0,ffffffff,1) at vm_page_alloc_contig+0x398 > contigmalloc(4000,c0627840,1,0,ffffffff) at contigmalloc+0xb5 > bus_dmamem_alloc(c455b280,c6531048,5,c6531044,ffffffff) at bus_dmamem_alloc+0xde > usb_block_allocmem(1,c51a913c,c479969c,c51a9100,c51a9100) at usb_block_allocmem+0x11a > usb_allocmem(c455f000,4000,0,c51a913c,e3c3bbc4) at usb_allocmem+0x11c > ehci_allocm(c455f000,c51a913c,4000,0,e3c3bbf0) at ehci_allocm+0x25 > usbd_transfer(c51a9100,c4816400,c503ac00,d9cc1000,4000) at usbd_transfer+0xec > umass_setup_transfer(d9cc1000,4000,4,c51a9100,e3c3bc1c) at umass_setup_transfer+0x49 > umass_bbb_state(c51b8c00,c503ac00,0,1f,0) at umass_bbb_state+0xd6 > usb_transfer_complete(c51b8c00,c51b8c70,adc,e3c3bcb0,0) at usb_transfer_complete+0x1e7 > ehci_softintr(c455f000,c05fd1d2,e3c3bcb0,c0499a28,e6047000) at ehci_softintr+0x17d > ehci_intr1(c455f000,0,c05fd1d2,295,1) at ehci_intr1+0x276 > ithread_execute_handlers(c45da8d0,c4510800,c05fd1d2,2f9,c45db1b0) at ithread_execute_handlers+0x128 > ithread_loop(c460c2f0,e3c3bd38,c05fcfab,32b,0) at ithread_loop+0x83 > fork_exit(c048b2e0,c460c2f0,e3c3bd38) at fork_exit+0xc3 > fork_trampoline() at fork_trampoline+0x8 > --- trap 0x1, eip = 0, esp = 0xe3c3bd6c, ebp = 0 --- > > Umass tries to allocate memory using bus_dmamem_alloc() with > BUS_DMA_NOWAIT flag, but contigmalloc() ignores the flag and simply can > sleep waiting for some memory to be reclaimed. > We don't allow to sleep in interrupt context, so the kernel panics. > > PS. I replaced the assertion on my laptop with a printf, because it was > triggered way too often. Please refer to the documentation: The flags parameter modifies contigmalloc()'s behaviour as follows: M_ZERO Causes the allocated physical memory to be zero filled. Other flags (if present) are ignored. -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\