Messages in this thread Patch in this message | | | Date | Thu, 28 Dec 2006 15:51:48 -0800 | From | Andrew Morton <> | Subject | Re: [Bug 7505] Linux-2.6.18 fails to boot on AMD64 machine |
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Could someone please test this?
From: Andrew Morton <akpm@osdl.org>
Various people have reported machines failing to boot since pci_bus_sem was switched from a spinlock to an rwsem.
The reason for this is that these people had "ide=" on the kernel commandline, and ide_setup() can end up calling PCI functions which do down_read(&pci_bus_sem).
Ard has worked out the call tree:
init/main.c start_kernel kernel/params.c parse_args("Booting kernel" kernel/params.c parse_one drivers/ide/ide.c ide_setup drivers/ide/ide.c init_ide_data drivers/ide/ide.c init_hwif_default include/asm-i386/ide.h ide_default_io_base(index) drivers/pci/search.c pci_find_device drivers/pci/search.c pci_find_subsys down_read(&pci_bus_sem);
down_read() will unconditionally enable interrupts and some early interrupt (source unknown) comes in and whacks the machine, apparently because the LDT isn't set up yet.
Fix that by avoiding taking the semaphore in the PCI code in this situation.
Cc: Ard -kwaak- van Breemen <ard@telegraafnet.nl> Cc: "Zhang, Yanmin" <yanmin.zhang@intel.com> Cc: Chuck Ebbert <76306.1226@compuserve.com> Cc: Yinghai Lu <yinghai.lu@amd.com> Cc: <take@libero.it> Cc: <agalanin@mera.ru> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Greg KH <greg@kroah.com> Signed-off-by: Andrew Morton <akpm@osdl.org> ---
drivers/pci/search.c | 10 ++++++++++ 1 files changed, 10 insertions(+)
diff -puN drivers/pci/search.c~pci-avoid-taking-pci_bus_sem-early-in-boot drivers/pci/search.c --- a/drivers/pci/search.c~pci-avoid-taking-pci_bus_sem-early-in-boot +++ a/drivers/pci/search.c @@ -259,6 +259,16 @@ pci_get_subsys(unsigned int vendor, unsi struct pci_dev *dev; WARN_ON(in_interrupt()); + + /* + * pci_get_subsys() can be called on the ide_setup() path, super-early + * in boot. But the down_read() will enable local interrupts, which + * can cause some machines to crash. So here we detect that situation + * and bail out early. + */ + if (unlikely(list_empty(pci_devices))) + return NULL; + down_read(&pci_bus_sem); n = from ? from->global_list.next : pci_devices.next; _ - 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/
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