* [PATCH] media: videobuf2: Set vma_flags in vb2_dma_sg_mmap @ 2026-02-15 17:42 ` Janne Grunau 2026-02-17 8:21 ` Marek Szyprowski 0 siblings, 1 reply; 2+ messages in thread From: Janne Grunau @ 2026-02-15 17:42 UTC (permalink / raw) To: Tomasz Figa, Marek Szyprowski, Mauro Carvalho Chehab, Andrzej Pietrasiewicz, Kyungmin Park, Hans Verkuil, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie, Simona Vetter Cc: linux-media, dri-devel, linux-kernel, stable, Janne Grunau vb2_dma_contig sets VMA flags VM_DONTEXPAND and VM_DONTDUMP and I do not see a reason why vb2_dma_sg should behave differently. This avoids hitting `WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));` in drm_gem_mmap_obj() during mmap() of an imported dma-buf from the out of tree Apple ISP camera capture driver which uses vb2_dma_sg_memops. gst-launch-1.0 v4l2src ! gtk4paintablesink [ 38.201528] ------------[ cut here ]------------ [ 38.202135] WARNING: CPU: 7 PID: 2362 at drivers/gpu/drm/drm_gem.c:1144 drm_gem_mmap_obj+0x1f8/0x210 [ 38.203278] Modules linked in: rfcomm snd_seq_dummy snd_hrtimer snd_seq snd_seq_device uinput nf_conntrack_netbios_ns nf_conntrack_broadcast nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables qrtr bnep nls_ascii i2c_dev loop fuse dm_multipath nfnetlink brcmfmac_wcc hid_magicmouse hci_bcm4377 brcmfmac brcmutil bluetooth ecdh_generic cfg80211 ecc btrfs xor xor_neon rfkill hid_apple raid6_pq joydev aop_als apple_nvmem_spmi industrialio snd_soc_aop apple_z2 snd_soc_cs42l84 tps6598x snd_soc_tas2764 macsmc_reboot spi_nor macsmc_hwmon rtc_macsmc gpio_macsmc macsmc_power regmap_spmi macsmc_input dockchannel_hid panel_summit appledrm nvme_apple dwc3 snd_soc_macaudio drm_client_lib nvme_core phy_apple_atc hwmon apple_sart apple_dockchannel macsmc apple_rtkit_helper spmi_apple_controller aop apple_wdt mfd_core nvmem_apple_efuses pinctrl_apple_gpio apple_isp apple_dcp videobuf2_dma_sg mux_core spi_apple [ 38.203300] videobuf2_memops i2c_pasemi_platform snd_soc_apple_mca videobuf2_v4l2 videodev clk_apple_nco videobuf2_common snd_pcm_dmaengine adpdrm asahi apple_admac adpdrm_mipi drm_dma_helper pwm_apple i2c_pasemi_core drm_display_helper mc cec apple_dart ofpart apple_soc_cpufreq leds_pwm phram [ 38.217677] CPU: 7 UID: 1000 PID: 2362 Comm: gst-launch-1.0 Tainted: G W 6.17.6+ #asahi-dev PREEMPT(full) [ 38.219040] Tainted: [W]=WARN [ 38.219398] Hardware name: Apple MacBook Pro (13-inch, M2, 2022) (DT) [ 38.220213] pstate: 21400005 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) [ 38.221088] pc : drm_gem_mmap_obj+0x1f8/0x210 [ 38.221643] lr : drm_gem_mmap_obj+0x78/0x210 [ 38.222178] sp : ffffc0008dc678e0 [ 38.222579] x29: ffffc0008dc678e0 x28: 0000000000042a97 x27: ffff8000b701b480 [ 38.223465] x26: 00000000000000fb x25: ffffc0008dc67d20 x24: ffffc0008dc67968 [ 38.224402] x23: ffff8000e3ca5600 x22: ffff8000265b7800 x21: ffff80003000c0c0 [ 38.225279] x20: 0000000000000000 x19: ffff8000b68c5200 x18: ffffc0008dc67968 [ 38.226151] x17: 0000000000000000 x16: 0000000000000000 x15: ffffc000810a30a8 [ 38.227042] x14: 00007fff637effff x13: 00005555de91ffff x12: 00007fff63293fff [ 38.227942] x11: 0000000000000000 x10: ffff8000184ecf08 x9 : ffffc0007a1900c8 [ 38.228824] x8 : ffffc0008dc67968 x7 : 0000000000000012 x6 : ffffc0015cf1c000 [ 38.229703] x5 : ffffc0008dc676a0 x4 : ffffc00081a27dc0 x3 : 0000000000000038 [ 38.230607] x2 : 0000000000000003 x1 : 0000000000000003 x0 : 00000000100000fb [ 38.231488] Call trace: [ 38.231806] drm_gem_mmap_obj+0x1f8/0x210 (P) [ 38.232342] drm_gem_mmap+0x140/0x260 [ 38.232813] __mmap_region+0x488/0x9a0 [ 38.233277] mmap_region+0xd0/0x148 [ 38.233703] do_mmap+0x350/0x5c0 [ 38.234148] vm_mmap_pgoff+0x14c/0x200 [ 38.234612] ksys_mmap_pgoff+0x150/0x208 [ 38.235107] __arm64_sys_mmap+0x34/0x50 [ 38.235611] invoke_syscall+0x50/0x120 [ 38.236075] el0_svc_common.constprop.0+0x48/0xf0 [ 38.236680] do_el0_svc+0x24/0x38 [ 38.237113] el0_svc+0x38/0x168 [ 38.237507] el0t_64_sync_handler+0xa0/0xe8 [ 38.238034] el0t_64_sync+0x198/0x1a0 [ 38.238491] ---[ end trace 0000000000000000 ]--- There were discussions in [1] at the end of 2023 that mmap() on imported dma-bufs should not be supported but as of v6.17 drm_gem_shmem_mmap() in drm_gem_shmem_helper.c still supports it. This might affect all gpu or accel drivers using drm_gem_shmem_mmap() or the wrapper drm_gem_shmem_object_mmap(). [1] https://lore.kernel.org/dri-devel/bc7f7844-0aa3-4802-b203-69d58e8be2fa@linux.intel.com/ Cc: stable@vger.kernel.org Fixes: 5ba3f757f059 ("[media] v4l: videobuf2: add DMA scatter/gather allocator") Signed-off-by: Janne Grunau <j@jannau.net> --- included DRM maintainers due to warning triggered from DRM code. --- drivers/media/common/videobuf2/videobuf2-dma-sg.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c index b3bf2173c14e1b3bedb8ab0bd60c889a0b97cbe3..7c30731cb9a57bebb3cf418e627e7c9f09ba8642 100644 --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c @@ -345,6 +345,7 @@ static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma) return err; } + vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP); /* * Use common vm_area operations to track buffer refcount. */ --- base-commit: 05f7e89ab9731565d8a62e3b5d1ec206485eeb0b change-id: 20260215-media-vb2-dma-sg-0fa33fdafdde Best regards, -- Janne Grunau <j@jannau.net> ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] media: videobuf2: Set vma_flags in vb2_dma_sg_mmap 2026-02-15 17:42 ` [PATCH] media: videobuf2: Set vma_flags in vb2_dma_sg_mmap Janne Grunau @ 2026-02-17 8:21 ` Marek Szyprowski 0 siblings, 0 replies; 2+ messages in thread From: Marek Szyprowski @ 2026-02-17 8:21 UTC (permalink / raw) To: Janne Grunau, Tomasz Figa, Mauro Carvalho Chehab, Kyungmin Park, Hans Verkuil, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, David Airlie, Simona Vetter Cc: linux-media, dri-devel, linux-kernel, stable On 15.02.2026 18:42, Janne Grunau wrote: > vb2_dma_contig sets VMA flags VM_DONTEXPAND and VM_DONTDUMP and I do not > see a reason why vb2_dma_sg should behave differently. This avoids > hitting `WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));` in > drm_gem_mmap_obj() during mmap() of an imported dma-buf from the out of > tree Apple ISP camera capture driver which uses vb2_dma_sg_memops. > > gst-launch-1.0 v4l2src ! gtk4paintablesink > > [ 38.201528] ------------[ cut here ]------------ > [ 38.202135] WARNING: CPU: 7 PID: 2362 at drivers/gpu/drm/drm_gem.c:1144 drm_gem_mmap_obj+0x1f8/0x210 > [ 38.203278] Modules linked in: rfcomm snd_seq_dummy snd_hrtimer > snd_seq snd_seq_device uinput nf_conntrack_netbios_ns > nf_conntrack_broadcast nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib > nft_reject_inet nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat > nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables qrtr bnep > nls_ascii i2c_dev loop fuse dm_multipath nfnetlink brcmfmac_wcc > hid_magicmouse hci_bcm4377 brcmfmac brcmutil bluetooth ecdh_generic > cfg80211 ecc btrfs xor xor_neon rfkill hid_apple raid6_pq joydev > aop_als apple_nvmem_spmi industrialio snd_soc_aop apple_z2 > snd_soc_cs42l84 tps6598x snd_soc_tas2764 macsmc_reboot spi_nor > macsmc_hwmon rtc_macsmc gpio_macsmc macsmc_power regmap_spmi > macsmc_input dockchannel_hid panel_summit appledrm nvme_apple dwc3 > snd_soc_macaudio drm_client_lib nvme_core phy_apple_atc hwmon > apple_sart apple_dockchannel macsmc apple_rtkit_helper > spmi_apple_controller aop apple_wdt mfd_core nvmem_apple_efuses > pinctrl_apple_gpio apple_isp apple_dcp videobuf2_dma_sg mux_core > spi_apple > [ 38.203300] videobuf2_memops i2c_pasemi_platform snd_soc_apple_mca videobuf2_v4l2 videodev clk_apple_nco videobuf2_common snd_pcm_dmaengine adpdrm asahi apple_admac adpdrm_mipi drm_dma_helper pwm_apple i2c_pasemi_core drm_display_helper mc cec apple_dart ofpart apple_soc_cpufreq leds_pwm phram > [ 38.217677] CPU: 7 UID: 1000 PID: 2362 Comm: gst-launch-1.0 Tainted: G W 6.17.6+ #asahi-dev PREEMPT(full) > [ 38.219040] Tainted: [W]=WARN > [ 38.219398] Hardware name: Apple MacBook Pro (13-inch, M2, 2022) (DT) > [ 38.220213] pstate: 21400005 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) > [ 38.221088] pc : drm_gem_mmap_obj+0x1f8/0x210 > [ 38.221643] lr : drm_gem_mmap_obj+0x78/0x210 > [ 38.222178] sp : ffffc0008dc678e0 > [ 38.222579] x29: ffffc0008dc678e0 x28: 0000000000042a97 x27: ffff8000b701b480 > [ 38.223465] x26: 00000000000000fb x25: ffffc0008dc67d20 x24: ffffc0008dc67968 > [ 38.224402] x23: ffff8000e3ca5600 x22: ffff8000265b7800 x21: ffff80003000c0c0 > [ 38.225279] x20: 0000000000000000 x19: ffff8000b68c5200 x18: ffffc0008dc67968 > [ 38.226151] x17: 0000000000000000 x16: 0000000000000000 x15: ffffc000810a30a8 > [ 38.227042] x14: 00007fff637effff x13: 00005555de91ffff x12: 00007fff63293fff > [ 38.227942] x11: 0000000000000000 x10: ffff8000184ecf08 x9 : ffffc0007a1900c8 > [ 38.228824] x8 : ffffc0008dc67968 x7 : 0000000000000012 x6 : ffffc0015cf1c000 > [ 38.229703] x5 : ffffc0008dc676a0 x4 : ffffc00081a27dc0 x3 : 0000000000000038 > [ 38.230607] x2 : 0000000000000003 x1 : 0000000000000003 x0 : 00000000100000fb > [ 38.231488] Call trace: > [ 38.231806] drm_gem_mmap_obj+0x1f8/0x210 (P) > [ 38.232342] drm_gem_mmap+0x140/0x260 > [ 38.232813] __mmap_region+0x488/0x9a0 > [ 38.233277] mmap_region+0xd0/0x148 > [ 38.233703] do_mmap+0x350/0x5c0 > [ 38.234148] vm_mmap_pgoff+0x14c/0x200 > [ 38.234612] ksys_mmap_pgoff+0x150/0x208 > [ 38.235107] __arm64_sys_mmap+0x34/0x50 > [ 38.235611] invoke_syscall+0x50/0x120 > [ 38.236075] el0_svc_common.constprop.0+0x48/0xf0 > [ 38.236680] do_el0_svc+0x24/0x38 > [ 38.237113] el0_svc+0x38/0x168 > [ 38.237507] el0t_64_sync_handler+0xa0/0xe8 > [ 38.238034] el0t_64_sync+0x198/0x1a0 > [ 38.238491] ---[ end trace 0000000000000000 ]--- > > There were discussions in [1] at the end of 2023 that mmap() on imported > dma-bufs should not be supported but as of v6.17 drm_gem_shmem_mmap() in > drm_gem_shmem_helper.c still supports it. > This might affect all gpu or accel drivers using drm_gem_shmem_mmap() or > the wrapper drm_gem_shmem_object_mmap(). > > [1] https://lore.kernel.org/dri-devel/bc7f7844-0aa3-4802-b203-69d58e8be2fa@linux.intel.com/ > > Cc: stable@vger.kernel.org > Fixes: 5ba3f757f059 ("[media] v4l: videobuf2: add DMA scatter/gather allocator") > Signed-off-by: Janne Grunau <j@jannau.net> This looks like an oversight from the beginning of videobuf2-dma-sg. Acked-by: Marek Szyprowski <m.szyprowski@samsung.com> > --- > included DRM maintainers due to warning triggered from DRM code. > --- > drivers/media/common/videobuf2/videobuf2-dma-sg.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/media/common/videobuf2/videobuf2-dma-sg.c b/drivers/media/common/videobuf2/videobuf2-dma-sg.c > index b3bf2173c14e1b3bedb8ab0bd60c889a0b97cbe3..7c30731cb9a57bebb3cf418e627e7c9f09ba8642 100644 > --- a/drivers/media/common/videobuf2/videobuf2-dma-sg.c > +++ b/drivers/media/common/videobuf2/videobuf2-dma-sg.c > @@ -345,6 +345,7 @@ static int vb2_dma_sg_mmap(void *buf_priv, struct vm_area_struct *vma) > return err; > } > > + vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP); > /* > * Use common vm_area operations to track buffer refcount. > */ > > --- > base-commit: 05f7e89ab9731565d8a62e3b5d1ec206485eeb0b > change-id: 20260215-media-vb2-dma-sg-0fa33fdafdde > > Best regards, Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland ^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-02-15 17:42 ` [PATCH] media: videobuf2: Set vma_flags in vb2_dma_sg_mmap Janne Grunau
2026-02-17 8:21 ` Marek Szyprowski
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