Panic in gen8_ggtt_insert_entries() with v6.5

Hello.

Since v6.5 kernel the following HW:

* Lenovo T460s laptop with Skylake GT2 [HD Graphics 520] (rev 07)
* Lenovo T490s laptop with WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02)

is affected by the following crash once KDE on either X11 or Wayland is started:

i915 0000:00:02.0: enabling device (0006 -> 0007)
i915 0000:00:02.0: vgaarb: deactivate vga console
i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=mem i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 1
fbcon: i915drmfb (fb0) is primary device
i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
…
memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=674 'kwin_wayland'

BUG: unable to handle page fault for address: ffffb422c2800000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 100000067 P4D 100000067 PUD 1001df067 PMD 10d1cf067 PTE 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 1 PID: 674 Comm: kwin_wayland Not tainted 6.5.0-pf1 #1 a6c58ff41a7b8bb16a19f5af9e0e9bce20f9f38d
Hardware name: LENOVO 20FAS2BM0F/20FAS2BM0F, BIOS N1CET90W (1.58 ) 11/15/2022
RIP: 0010:gen8_ggtt_insert_entries+0xc2/0x140 [i915]
…
Call Trace:
 <TASK>
 intel_ggtt_bind_vma+0x3e/0x60 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_bind+0x216/0x4b0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_pin_ww+0x405/0xa80 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __i915_ggtt_pin+0x5a/0x130 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_ggtt_pin+0x78/0x1f0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __intel_context_do_pin_ww+0x312/0x700 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_do_execbuffer+0xfc6/0x2720 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_execbuffer2_ioctl+0x111/0x260 [i915 a83fdc6539431252dba13053979a8b680af86836]
 drm_ioctl_kernel+0xca/0x170
 drm_ioctl+0x30f/0x580
 __x64_sys_ioctl+0x94/0xd0
 do_syscall_64+0x5d/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

…
note: kwin_wayland[674] exited with irqs disabled

RIP seems to translate into this:

$ scripts/faddr2line drivers/gpu/drm/i915/gt/intel_ggtt.o gen8_ggtt_insert_entries+0xc2
gen8_ggtt_insert_entries+0xc2/0x150:
writeq at /home/pf/work/devel/own/pf-kernel/linux/./arch/x86/include/asm/io.h:99
(inlined by) gen8_set_pte at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:257
(inlined by) gen8_ggtt_insert_entries at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:300

Probably, recent PTE-related changes are relevant:

$ git log --oneline --no-merges v6.4..v6.5 -- drivers/gpu/drm/i915/gt/intel_ggtt.c
3532e75dfadcf drm/i915/uc: perma-pin firmwares
4722e2ebe6f21 drm/i915/gt: Fix second parameter type of pre-gen8 pte_encode callbacks
9275277d53248 drm/i915: use pat_index instead of cache_level
5e352e32aec23 drm/i915: preparation for using PAT index
341ad0e8e2542 drm/i915/mtl: Add PTE encode function

Also note Lenovo T14s laptop with TigerLake-LP GT2 [Iris Xe Graphics] (rev 01) is not affected by this issue.

Full dmesg with DRM debug enabled is available in the bugreport I've reported earlier [1]. I'm sending this email to make the issue more visible.

Please help.

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

/cc Matthew Wilcox and Andrew Morton because of folios (please see below).

Quoted 64 lines · On sobota 2. září 2023 18:14:12 CEST Oleksandr Natalenko wrote:

Hello.

Since v6.5 kernel the following HW:

* Lenovo T460s laptop with Skylake GT2 [HD Graphics 520] (rev 07)
* Lenovo T490s laptop with WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02)

is affected by the following crash once KDE on either X11 or Wayland is started:

i915 0000:00:02.0: enabling device (0006 -> 0007)
i915 0000:00:02.0: vgaarb: deactivate vga console
i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=mem i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 1
fbcon: i915drmfb (fb0) is primary device
i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
…
memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=674 'kwin_wayland'

BUG: unable to handle page fault for address: ffffb422c2800000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 100000067 P4D 100000067 PUD 1001df067 PMD 10d1cf067 PTE 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 1 PID: 674 Comm: kwin_wayland Not tainted 6.5.0-pf1 #1 a6c58ff41a7b8bb16a19f5af9e0e9bce20f9f38d
Hardware name: LENOVO 20FAS2BM0F/20FAS2BM0F, BIOS N1CET90W (1.58 ) 11/15/2022
RIP: 0010:gen8_ggtt_insert_entries+0xc2/0x140 [i915]
…
Call Trace:
 <TASK>
 intel_ggtt_bind_vma+0x3e/0x60 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_bind+0x216/0x4b0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_pin_ww+0x405/0xa80 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __i915_ggtt_pin+0x5a/0x130 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_ggtt_pin+0x78/0x1f0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __intel_context_do_pin_ww+0x312/0x700 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_do_execbuffer+0xfc6/0x2720 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_execbuffer2_ioctl+0x111/0x260 [i915 a83fdc6539431252dba13053979a8b680af86836]
 drm_ioctl_kernel+0xca/0x170
 drm_ioctl+0x30f/0x580
 __x64_sys_ioctl+0x94/0xd0
 do_syscall_64+0x5d/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

…
note: kwin_wayland[674] exited with irqs disabled

RIP seems to translate into this:

$ scripts/faddr2line drivers/gpu/drm/i915/gt/intel_ggtt.o gen8_ggtt_insert_entries+0xc2
gen8_ggtt_insert_entries+0xc2/0x150:
writeq at /home/pf/work/devel/own/pf-kernel/linux/./arch/x86/include/asm/io.h:99
(inlined by) gen8_set_pte at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:257
(inlined by) gen8_ggtt_insert_entries at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:300

Probably, recent PTE-related changes are relevant:

$ git log --oneline --no-merges v6.4..v6.5 -- drivers/gpu/drm/i915/gt/intel_ggtt.c
3532e75dfadcf drm/i915/uc: perma-pin firmwares
4722e2ebe6f21 drm/i915/gt: Fix second parameter type of pre-gen8 pte_encode callbacks
9275277d53248 drm/i915: use pat_index instead of cache_level
5e352e32aec23 drm/i915: preparation for using PAT index
341ad0e8e2542 drm/i915/mtl: Add PTE encode function

Also note Lenovo T14s laptop with TigerLake-LP GT2 [Iris Xe Graphics] (rev 01) is not affected by this issue.

Quoted 7 lines

Full dmesg with DRM debug enabled is available in the bugreport I've reported earlier [1]. I'm sending this email to make the issue more visible.

Please help.

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Matthew,

Andrzej asked me to try to revert commits 0b62af28f249, e0b72c14d8dc and 1e0877d58b1e, and reverting those fixed the i915 crash for me. The e0b72c14d8dc and 1e0877d58b1e commits look like just prerequisites, so I assume 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") is the culprit here.

Could you please check this?

Our conversation with Andrzej is available at drm-intel GitLab [1].

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

/cc Bagas as well (see below).

Quoted 83 lines · On úterý 19. září 2023 10:26:42 CEST Oleksandr Natalenko wrote:

/cc Matthew Wilcox and Andrew Morton because of folios (please see below).

Quoted 64 lines · On sobota 2. září 2023 18:14:12 CEST Oleksandr Natalenko wrote:

Hello.

Since v6.5 kernel the following HW:

* Lenovo T460s laptop with Skylake GT2 [HD Graphics 520] (rev 07)
* Lenovo T490s laptop with WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02)

is affected by the following crash once KDE on either X11 or Wayland is started:

i915 0000:00:02.0: enabling device (0006 -> 0007)
i915 0000:00:02.0: vgaarb: deactivate vga console
i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=mem i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 1
fbcon: i915drmfb (fb0) is primary device
i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
…
memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=674 'kwin_wayland'

BUG: unable to handle page fault for address: ffffb422c2800000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 100000067 P4D 100000067 PUD 1001df067 PMD 10d1cf067 PTE 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 1 PID: 674 Comm: kwin_wayland Not tainted 6.5.0-pf1 #1 a6c58ff41a7b8bb16a19f5af9e0e9bce20f9f38d
Hardware name: LENOVO 20FAS2BM0F/20FAS2BM0F, BIOS N1CET90W (1.58 ) 11/15/2022
RIP: 0010:gen8_ggtt_insert_entries+0xc2/0x140 [i915]
…
Call Trace:
 <TASK>
 intel_ggtt_bind_vma+0x3e/0x60 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_bind+0x216/0x4b0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_pin_ww+0x405/0xa80 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __i915_ggtt_pin+0x5a/0x130 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_ggtt_pin+0x78/0x1f0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __intel_context_do_pin_ww+0x312/0x700 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_do_execbuffer+0xfc6/0x2720 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_execbuffer2_ioctl+0x111/0x260 [i915 a83fdc6539431252dba13053979a8b680af86836]
 drm_ioctl_kernel+0xca/0x170
 drm_ioctl+0x30f/0x580
 __x64_sys_ioctl+0x94/0xd0
 do_syscall_64+0x5d/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

…
note: kwin_wayland[674] exited with irqs disabled

RIP seems to translate into this:

$ scripts/faddr2line drivers/gpu/drm/i915/gt/intel_ggtt.o gen8_ggtt_insert_entries+0xc2
gen8_ggtt_insert_entries+0xc2/0x150:
writeq at /home/pf/work/devel/own/pf-kernel/linux/./arch/x86/include/asm/io.h:99
(inlined by) gen8_set_pte at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:257
(inlined by) gen8_ggtt_insert_entries at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:300

Probably, recent PTE-related changes are relevant:

$ git log --oneline --no-merges v6.4..v6.5 -- drivers/gpu/drm/i915/gt/intel_ggtt.c
3532e75dfadcf drm/i915/uc: perma-pin firmwares
4722e2ebe6f21 drm/i915/gt: Fix second parameter type of pre-gen8 pte_encode callbacks
9275277d53248 drm/i915: use pat_index instead of cache_level
5e352e32aec23 drm/i915: preparation for using PAT index
341ad0e8e2542 drm/i915/mtl: Add PTE encode function

Also note Lenovo T14s laptop with TigerLake-LP GT2 [Iris Xe Graphics] (rev 01) is not affected by this issue.

Quoted 7 lines

Full dmesg with DRM debug enabled is available in the bugreport I've reported earlier [1]. I'm sending this email to make the issue more visible.

Please help.

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Matthew,

Andrzej asked me to try to revert commits 0b62af28f249, e0b72c14d8dc and 1e0877d58b1e, and reverting those fixed the i915 crash for me. The e0b72c14d8dc and 1e0877d58b1e commits look like just prerequisites, so I assume 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") is the culprit here.

Could you please check this?

Our conversation with Andrzej is available at drm-intel GitLab [1].

Quoted 3 lines

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Bagas,

would you mind adding this to the regression tracker please?

…

Quoted 6 lines

Quoted 1 line

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Bagas,

would you mind adding this to the regression tracker please?

Will add shortly, thanks!

Andrzej asked me to try to revert commits 0b62af28f249, e0b72c14d8dc and 1e0877d58b1e, and reverting those fixed the i915 crash for me. The e0b72c14d8dc and 1e0877d58b1e commits look like just prerequisites, so I assume 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") is the culprit here.

Could you please check this?

Our conversation with Andrzej is available at drm-intel GitLab [1].

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Could I ask you to try this patch? I'll follow up with another patch later because I think I made another assumption that may not be valid.

Quoted 9 lines · Oleksandr Natalenko

Andrzej asked me to try to revert commits 0b62af28f249, e0b72c14d8dc and 1e0877d58b1e, and reverting those fixed the i915 crash for me. The e0b72c14d8dc and 1e0877d58b1e commits look like just prerequisites, so I assume 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") is the culprit here.

Could you please check this?

Our conversation with Andrzej is available at drm-intel GitLab [1].

Thanks.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Wow, that is some great debugging. Thanks for all the time & effort you and others have invested. Sorry for breaking your system.

You're almost right about the "prerequisites", but it's in the other direction; 0b62af28f249 is a prerequisite for the later two cleanups, so reverting all three is necessary to test 0b62af28f249.

It seems to me that you've isolated the problem to constructing overly long sg lists. I didn't realise that was going to be a problem, so that's my fault.

Could I ask you to try this patch? I'll follow up with another patch later because I think I made another assumption that may not be valid.

drivers/gpu/drm/i915/gem/i915_gem_shmem.c +7 -4

index 8f1633c3fb93..73a4a4eb29e0 100644
@@ -100,6 +100,7 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 	st->nents = 0;
 	for (i = 0; i < page_count; i++) {
 		struct folio *folio;
+		unsigned long nr_pages;
 		const unsigned int shrink[] = {
 			I915_SHRINK_BOUND | I915_SHRINK_UNBOUND,
 			0,

@@ -150,6 +151,8 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 			}
 		} while (1);
 
+		nr_pages = min_t(unsigned long,
+				folio_nr_pages(folio), page_count - i);
 		if (!i ||
 		    sg->length >= max_segment ||
 		    folio_pfn(folio) != next_pfn) {

@@ -157,13 +160,13 @@ int shmem_sg_alloc_table(struct drm_i915_private *i915, struct sg_table *st,
 				sg = sg_next(sg);
 
 			st->nents++;
-			sg_set_folio(sg, folio, folio_size(folio), 0);
+			sg_set_folio(sg, folio, nr_pages * PAGE_SIZE, 0);
 		} else {
 			/* XXX: could overflow? */
-			sg->length += folio_size(folio);
+			sg->length += nr_pages * PAGE_SIZE;
 		}
-		next_pfn = folio_pfn(folio) + folio_nr_pages(folio);
-		i += folio_nr_pages(folio) - 1;
+		next_pfn = folio_pfn(folio) + nr_pages;
+		i += nr_pages - 1;
 
 		/* Check that the i965g/gm workaround works. */
 		GEM_BUG_ON(gfp & __GFP_DMA32 && next_pfn >= 0x00100000UL);

I can confirm this one fixes the issue for me on T460s laptop. Thank you!

Should you submit it, please add:

Fixes 0b62af28f2 ("i915: convert shmem_sg_free_table() to use a folio_batch")

Hello.

Since v6.5 kernel the following HW:

* Lenovo T460s laptop with Skylake GT2 [HD Graphics 520] (rev 07)
* Lenovo T490s laptop with WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02)

is affected by the following crash once KDE on either X11 or Wayland is started:

i915 0000:00:02.0: enabling device (0006 -> 0007)
i915 0000:00:02.0: vgaarb: deactivate vga console
i915 0000:00:02.0: vgaarb: changed VGA decodes: olddecodes=io+mem,decodes=io+mem:owns=mem i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/skl_dmc_ver1_27.bin (v1.27) [drm] Initialized i915 1.6.0 20201103 for 0000:00:02.0 on minor 1
fbcon: i915drmfb (fb0) is primary device
i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
…
memfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=674 'kwin_wayland'

BUG: unable to handle page fault for address: ffffb422c2800000
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 100000067 P4D 100000067 PUD 1001df067 PMD 10d1cf067 PTE 0
Oops: 0002 [#1] PREEMPT SMP PTI
CPU: 1 PID: 674 Comm: kwin_wayland Not tainted 6.5.0-pf1 #1 a6c58ff41a7b8bb16a19f5af9e0e9bce20f9f38d
Hardware name: LENOVO 20FAS2BM0F/20FAS2BM0F, BIOS N1CET90W (1.58 ) 11/15/2022
RIP: 0010:gen8_ggtt_insert_entries+0xc2/0x140 [i915]
…
Call Trace:
 <TASK>
 intel_ggtt_bind_vma+0x3e/0x60 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_bind+0x216/0x4b0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_vma_pin_ww+0x405/0xa80 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __i915_ggtt_pin+0x5a/0x130 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_ggtt_pin+0x78/0x1f0 [i915 a83fdc6539431252dba13053979a8b680af86836]
 __intel_context_do_pin_ww+0x312/0x700 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_do_execbuffer+0xfc6/0x2720 [i915 a83fdc6539431252dba13053979a8b680af86836]
 i915_gem_execbuffer2_ioctl+0x111/0x260 [i915 a83fdc6539431252dba13053979a8b680af86836]
 drm_ioctl_kernel+0xca/0x170
 drm_ioctl+0x30f/0x580
 __x64_sys_ioctl+0x94/0xd0
 do_syscall_64+0x5d/0x90
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

…
note: kwin_wayland[674] exited with irqs disabled

RIP seems to translate into this:

$ scripts/faddr2line drivers/gpu/drm/i915/gt/intel_ggtt.o gen8_ggtt_insert_entries+0xc2
gen8_ggtt_insert_entries+0xc2/0x150:
writeq at /home/pf/work/devel/own/pf-kernel/linux/./arch/x86/include/asm/io.h:99
(inlined by) gen8_set_pte at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:257
(inlined by) gen8_ggtt_insert_entries at /home/pf/work/devel/own/pf-kernel/linux/drivers/gpu/drm/i915/gt/intel_ggtt.c:300

Probably, recent PTE-related changes are relevant:

$ git log --oneline --no-merges v6.4..v6.5 -- drivers/gpu/drm/i915/gt/intel_ggtt.c
3532e75dfadcf drm/i915/uc: perma-pin firmwares
4722e2ebe6f21 drm/i915/gt: Fix second parameter type of pre-gen8 pte_encode callbacks
9275277d53248 drm/i915: use pat_index instead of cache_level
5e352e32aec23 drm/i915: preparation for using PAT index
341ad0e8e2542 drm/i915/mtl: Add PTE encode function

Also note Lenovo T14s laptop with TigerLake-LP GT2 [Iris Xe Graphics] (rev 01) is not affected by this issue.

Full dmesg with DRM debug enabled is available in the bugreport I've reported earlier [1]. I'm sending this email to make the issue more visible.

[1] https://gitlab.freedesktop.org/drm/intel/-/issues/9256

Quoted 5 lines · Oleksandr Natalenko

Since v6.5 kernel the following HW:

* Lenovo T460s laptop with Skylake GT2 [HD Graphics 520] (rev 07)
* Lenovo T490s laptop with WhiskeyLake-U GT2 [UHD Graphics 620] (rev 02)

#regzbot ^introduced: 0b62af28f249b9
#regzbot title: gen8_ggtt_insert_entries() panic on Lenovo T14s (Tiger Lake) due to folio_batch() on shmem_sg_free_table() #regzbot link: https://gitlab.freedesktop.org/drm/intel/-/issues/9256

-:7: WARNING:COMMIT_LOG_LONG_LINE: Prefer a maximum 75 chars per line (possible unwrapped commit description?) #7:

Quoted 1 line

Andrzej asked me to try to revert commits 0b62af28f249, e0b72c14d8dc and 1e0877d58b1e, and reverting those fixed the i915 crash for me. The e0b72c14d8dc and 1e0877d58b1e commits look like just prerequisites, so I assume 0b62af28f249 ("i915: convert shmem_sg_free_table() to use a folio_batch") is the culprit here.