On Wed, Jun 30, 2021 at 07:44:21PM +0200, Thierry Reding wrote:
> On Wed, Jun 30, 2021 at 01:12:26PM +0200, Marek Szyprowski wrote:
> > Hi Leon,
> >
> > On 29.06.2021 10:40, Leon Romanovsky wrote:
> > > From: Maor Gottlieb <maorg@xxxxxxxxxx>
> > >
> > > orig_nents should represent the number of entries with pages,
> > > but __sg_alloc_table_from_pages sets orig_nents as the number of
> > > total entries in the table. This is wrong when the API is used for
> > > dynamic allocation where not all the table entries are mapped with
> > > pages. It wasn't observed until now, since RDMA umem who uses this
> > > API in the dynamic form doesn't use orig_nents implicit or explicit
> > > by the scatterlist APIs.
> > >
> > > Fix it by:
> > > 1. Set orig_nents as number of entries with pages also in
> > > __sg_alloc_table_from_pages.
> > > 2. Add a new field total_nents to reflect the total number of entries
> > > in the table. This is required for the release flow (sg_free_table).
> > > This filed should be used internally only by scatterlist.
> > >
> > > Fixes: 07da1223ec93 ("lib/scatterlist: Add support in dynamic allocation of SG table from pages")
> > > Signed-off-by: Maor Gottlieb <maorg@xxxxxxxxxx>
> > > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
> >
> > This patch landed in linux-next 20210630 as commit a52724456928
> > ("lib/scatterlist: Fix wrong update of orig_nents"). It causes serious
> > regression in DMA-IOMMU integration, which can be observed for example
> > on ARM Juno board during boot:
> >
> > Unable to handle kernel paging request at virtual address 00376f42a6e40454
> > Mem abort info:
> > ESR = 0x96000004
> > EC = 0x25: DABT (current EL), IL = 32 bits
> > SET = 0, FnV = 0
> > EA = 0, S1PTW = 0
> > FSC = 0x04: level 0 translation fault
> > Data abort info:
> > ISV = 0, ISS = 0x00000004
> > CM = 0, WnR = 0
> > [00376f42a6e40454] address between user and kernel address ranges
> > Internal error: Oops: 96000004 [#1] PREEMPT SMP
> > Modules linked in:
> > CPU: 2 PID: 1 Comm: swapper/0 Not tainted 5.13.0-next-20210630+ #3585
> > Hardware name: ARM Juno development board (r1) (DT)
> > pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
> > pc : __sg_free_table+0x60/0xa0
> > lr : __sg_free_table+0x7c/0xa0
> > ..
> > Call trace:
> > __sg_free_table+0x60/0xa0
> > sg_free_table+0x1c/0x28
> > iommu_dma_alloc+0xc8/0x388
> > dma_alloc_attrs+0xcc/0xf0
> > dmam_alloc_attrs+0x68/0xb8
> > sil24_port_start+0x60/0xe0
> > ata_host_start.part.32+0xbc/0x208
> > ata_host_activate+0x64/0x150
> > sil24_init_one+0x1e8/0x268
> > local_pci_probe+0x3c/0xa0
> > pci_device_probe+0x128/0x1c8
> > really_probe+0x138/0x2d0
> > __driver_probe_device+0x78/0xd8
> > driver_probe_device+0x40/0x110
> > __driver_attach+0xcc/0x118
> > bus_for_each_dev+0x68/0xc8
> > driver_attach+0x20/0x28
> > bus_add_driver+0x168/0x1f8
> > driver_register+0x60/0x110
> > __pci_register_driver+0x5c/0x68
> > sil24_pci_driver_init+0x20/0x28
> > do_one_initcall+0x84/0x450
> > kernel_init_freeable+0x31c/0x38c
> > kernel_init+0x20/0x120
> > ret_from_fork+0x10/0x18
> > Code: d37be885 6b01007f 52800004 540000a2 (f8656813)
> > ---[ end trace 4ba4f0c9c48711a1 ]---
> > Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
> >
> > It looks that some changes to the scatterlist structures are missing
> > outside of the lib/scatterlist.c.
> >
> > For now I would suggest to revert this change.
>
> I see a very similar crash on Tegra during the HDA driver's probe.
>
> Leon, let me know if you need a tester for a replacement patch.
With a great pleasure, I'll contact you offline when we prepare it.
For now, this patch will be dropped.
Thanks
>
> Thanks,
> Thierry
