On 07/02/2018 01:33 PM, Lorenzo Pieralisi wrote: >>>>> When testing the R-Car PCIe driver on the Condor board, I noticed that iff >>>>> I left the PCIe PHY driver disabled, the kernel crashed with this BUG: >>>>> >>>>> [ 1.225819] kernel BUG at lib/ioremap.c:72! >>>>> [ 1.230007] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP >>>>> [ 1.235496] Modules linked in: >>>>> [ 1.238561] CPU: 0 PID: 39 Comm: kworker/0:1 Not tainted 4.17.0-dirty >>>>> #1092 >>>>> [ 1.245526] Hardware name: Renesas Condor board based on r8a77980 (DT) >>>>> [ 1.252075] Workqueue: events deferred_probe_work_func >>>>> [ 1.257220] pstate: 80000005 (Nzcv daif -PAN -UAO) >>>>> [ 1.262024] pc : ioremap_page_range+0x370/0x3c8 >>>>> [ 1.266558] lr : ioremap_page_range+0x40/0x3c8 >>>>> [ 1.271002] sp : ffff000008da39e0 >>>>> [ 1.274317] x29: ffff000008da39e0 x28: 00e8000000000f07 >>>>> [ 1.279636] x27: ffff7dfffee00000 x26: 0140000000000000 >>>>> [ 1.284954] x25: ffff7dfffef00000 x24: 00000000000fe100 >>>>> [ 1.290272] x23: ffff80007b906000 x22: ffff000008ab8000 >>>>> [ 1.295590] x21: ffff000008bb1d58 x20: ffff7dfffef00000 >>>>> [ 1.300909] x19: ffff800009c30fb8 x18: 0000000000000001 >>>>> [ 1.306226] x17: 00000000000152d0 x16: 00000000014012d0 >>>>> [ 1.311544] x15: 0000000000000000 x14: 0720072007200720 >>>>> [ 1.316862] x13: 0720072007200720 x12: 0720072007200720 >>>>> [ 1.322180] x11: 0720072007300730 x10: 00000000000000ae >>>>> [ 1.327498] x9 : 0000000000000000 x8 : ffff7dffff000000 >>>>> [ 1.332816] x7 : 0000000000000000 x6 : 0000000000000100 >>>>> [ 1.338134] x5 : 0000000000000000 x4 : 000000007b906000 >>>>> [ 1.343452] x3 : ffff80007c61a880 x2 : ffff7dfffeefffff >>>>> [ 1.348770] x1 : 0000000040000000 x0 : 00e80000fe100f07 >>>>> [ 1.354090] Process kworker/0:1 (pid: 39, stack limit = 0x >>>>> (ptrval)) >>>>> [ 1.361056] Call trace: >>>>> [ 1.363504] ioremap_page_range+0x370/0x3c8 >>>>> [ 1.367695] pci_remap_iospace+0x7c/0xac >>>>> [ 1.371624] pci_parse_request_of_pci_ranges+0x13c/0x190 >>>>> [ 1.376945] rcar_pcie_probe+0x4c/0xb04 >>>>> [ 1.380786] platform_drv_probe+0x50/0xbc >>>>> [ 1.384799] driver_probe_device+0x21c/0x308 >>>>> [ 1.389072] __device_attach_driver+0x98/0xc8 >>>>> [ 1.393431] bus_for_each_drv+0x54/0x94 >>>>> [ 1.397269] __device_attach+0xc4/0x12c >>>>> [ 1.401107] device_initial_probe+0x10/0x18 >>>>> [ 1.405292] bus_probe_device+0x90/0x98 >>>>> [ 1.409130] deferred_probe_work_func+0xb0/0x150 >>>>> [ 1.413756] process_one_work+0x12c/0x29c >>>>> [ 1.417768] worker_thread+0x200/0x3fc >>>>> [ 1.421522] kthread+0x108/0x134 >>>>> [ 1.424755] ret_from_fork+0x10/0x18 >>>>> [ 1.428334] Code: f9004ba2 54000080 aa0003fb 17ffff48 (d4210000) >>>>> >>>>> It turned out that pci_remap_iospace() wasn't undone when the driver's >>>>> probe failed, and since devm_phy_optional_get() returned -EPROBE_DEFER, >>>>> the probe was retried, finally causing the BUG due to trying to remap >>>>> already remapped pages. >>>>> >>>>> The most feasible solution seems to introduce devm_pci_remap_iospace() >>>>> and call it instead of pci_remap_iospace(), so that the pages get unmapped >>>>> automagically on any probe failure. >>>>> >>>>> And while fixing pci_parse_request_of_pci_ranges(), aslo fix the other >>>>> drivers that have probably copied the bad example... >>>>> >>>>> Fixes: 4e64dbe226e7 ("PCI: generic: Expose pci_host_common_probe() for >>>>> use by other drivers") >>>>> Fixes: cbce7900598c ("PCI: designware: Make driver arch-agnostic") >>>>> Fixes: 8c39d710363c ("PCI: aardvark: Add Aardvark PCI host controller >>>>> driver") >>>>> Fixes: d3c68e0a7e34 ("PCI: faraday: Add Faraday Technology FTPCI100 PCI >>>>> Host Bridge driver") >>>>> Fixes: 68a15eb7bd0c ("PCI: v3-semi: Add V3 Semiconductor PCI host driver") >>>>> Fixes: b7e78170efd4 ("PCI: versatile: Add DT-based ARM Versatile PB PCIe >>>>> host driver") >>>>> Fixes: 5f6b6ccdbe1c ("PCI: xgene: Add APM X-Gene PCIe driver") >>>>> Fixes: 637cfacae96f ("PCI: mediatek: Add MediaTek PCIe host controller >>>>> support") >>>>> Signed-off-by: Sergei Shtylyov <sergei.shtyl...@cogentembedded.com> >>>>> Cc: sta...@vger.kernel.org >>>> >>>> Let me know if you want me to take this, Lorenzo, otherwise: >>>> s/pci: fix/PCI: Fix/ and >>>> >>>> Acked-by: Bjorn Helgaas <bhelg...@google.com> >>> >>> Thank you Bjorn, yes it could go in as a fix but IMO it has to be split, >>> more so given the stable tag (and I think that each "Fixes" tag should >>> be self-contained), >> >> It cannot be self-contained because it'll depend on the initial >> commit adding devm_pci_remap_iobase(). If you mean finding the >> earliest broken driver and introduce the deviec managed API while >> fixing it and then make use of that >> API in the subsequent patches, that surely can be done. > > Yes I think that's the best course of action.
OK! :-) >>> merging it as-is would give Greg (and us) a >>> headache when it comes to backporting it. >> >> The patch interdependency would give him headache too, and I was >> hoping to relieve those with the monilitic patch. :-) > > The problem is that if any of the fixes has to be reverted we have > to revert the whole thing instead of just the problematic patch, > which, given that we are sending this to stable kernels may easily > turn out quite complicated. > > So, I would add the new API along with the earliest broken driver > and mark it for stable. > > In the same thread, add all other fixes (one per patch) without the > stable tag. When the first fix gets merged into the mainline (and > consequently goes to stable) we can send the stable backports for the > remainder of fixes. > > How does that sound ? I think the -stable maintainers are actively looking at the Fixes: tags these days, not only at sta...@vger.kernel.org. I can do thsat >>> Honestly I think it is best to split it up and send it for v4.19 but >>> I am happy to hear other options. >> >> I disagree about 4.19. The R-Car PCIe situation is as follows: >> given me missing to get the PHY driver merged into 4.18 (and the >> gen3 PCIe stuff successfully merged into 4.18), the user is bound to >> have PCIe not working (if he doesn't refer to the PHY driver in DT) >> or encounter a kernel BUG (if he does refer to the PHY driver), thus s/driver/device/, of course. :-) >> I'd like this BUG to be fixed in 4.18 time frame... > > We shall try, please let me know if you are able to respin asap, > we already have a bunch of fixes queued. I can probably try -- despite I'm on vacations and the football championship is still going on. :-) > Thanks for putting it together, > Lorenzo MBR, Sergei