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Date: Wed, 26 Jun 2024 08:04:21 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
Cc: robh@...nel.org, broonie@...nel.org, catalin.marinas@....com,
conor@...nel.org, devicetree@...r.kernel.org, hch@....de,
iommu@...ts.linux.dev, kernel@...cinc.com,
linux-kernel@...r.kernel.org, m.szyprowski@...sung.com,
oe-kbuild-all@...ts.linux.dev, robin.murphy@....com,
saravanak@...gle.com, will@...nel.org
Subject: Re: [PATCH v2] of: reserved_mem: Restructure code to call reserved
mem init functions earlier
On Wed, Jun 19, 2024 at 05:10:27PM -0700, Oreoluwa Babatunde wrote:
> After all the reserved memory regions have been added to the
> reserved_mem array, a region specific initialization function is called
> on each of reserved memory regions in a loop to initialize them.
>
> With recent changes made to allow the reserved_mem array be dynamically
> allocated, the cma reserved memory regions are not initialized until
> after the page tables are setup. This causes the warning seen in the
> dump stack below:
>
> WARNING: CPU: 0 PID: 1 at mm/memory.c:2789 __apply_to_page_range+0x360/0x380
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.10.0-rc1-00007-ga46cccb0ee2d #1
> Hardware name: Generic DT based system
> Call trace:
> unwind_backtrace from show_stack+0x18/0x1c
> show_stack from dump_stack_lvl+0x54/0x68
> dump_stack_lvl from __warn+0x74/0x114
> __warn from warn_slowpath_fmt+0x13c/0x1c0
> warn_slowpath_fmt from __apply_to_page_range+0x360/0x380
> __apply_to_page_range from apply_to_page_range+0x24/0x2c
> apply_to_page_range from __alloc_from_contiguous+0xc4/0x158
> __alloc_from_contiguous from cma_allocator_alloc+0x3c/0x44
> cma_allocator_alloc from arch_dma_alloc+0x128/0x2b4
> arch_dma_alloc from dma_alloc_attrs+0x90/0x150
> dma_alloc_attrs from drm_gem_dma_create+0xa4/0x13c
> drm_gem_dma_create from drm_gem_dma_create_with_handle+0x24/0xac
> drm_gem_dma_create_with_handle from drm_gem_dma_dumb_create+0x44/0x50
> drm_gem_dma_dumb_create from drm_client_framebuffer_create+0x9c/0x164
> drm_client_framebuffer_create from drm_fbdev_dma_helper_fb_probe+0x84/0x23c
> drm_fbdev_dma_helper_fb_probe from __drm_fb_helper_initial_config_and_unlock+0x2e4/0x4f8
> __drm_fb_helper_initial_config_and_unlock from drm_fbdev_dma_client_hotplug+0x74/0xb8
> drm_fbdev_dma_client_hotplug from drm_client_register+0x5c/0x98
> drm_client_register from aspeed_gfx_probe+0x278/0x3c0
> aspeed_gfx_probe from platform_probe+0x60/0xb8
> platform_probe from really_probe+0xd4/0x3b4
> really_probe from __driver_probe_device+0x90/0x1dc
> __driver_probe_device from driver_probe_device+0x38/0xd0
> driver_probe_device from __driver_attach+0x118/0x1dc
> __driver_attach from bus_for_each_dev+0x84/0xd4
> bus_for_each_dev from bus_add_driver+0xec/0x1f0
> bus_add_driver from driver_register+0x84/0x11c
> driver_register from do_one_initcall+0x84/0x1c8
> do_one_initcall from kernel_init_freeable+0x1a4/0x230
> kernel_init_freeable from kernel_init+0x1c/0x138
> kernel_init from ret_from_fork+0x14/0x28
> Exception stack(0x9f015fb0 to 0x9f015ff8)
> 5fa0: 00000000 00000000 00000000 00000000
> 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000
> ---[ end trace 0000000000000000 ]---
> aspeed_gfx 1e6e6000.display: [drm] fb0: aspeed-gfx-drmd frame buffer device
>
> Hence, restructure the code to initialize the regions as soon as each
> of them are added to the reserved_mem array.
>
> Fixes: a46cccb0ee2d ("of: reserved_mem: Restruture how the reserved memory regions are processed")
> Signed-off-by: Oreoluwa Babatunde <quic_obabatun@...cinc.com>
This resolves the warning that I see and I see no other warnings
introduced in any of my virtual boot tests.
Tested-by: Nathan Chancellor <nathan@...nel.org>
> ---
> v2:
> - Fix kernel-doc for of_init_reserved_mem_node() in response to the
> below warning from v1:
> https://lore.kernel.org/all/202406181626.126X1Nbz-lkp@intel.com/
>
> v1:
> https://lore.kernel.org/all/20240617193357.3929092-1-quic_obabatun@quicinc.com/
>
> drivers/of/fdt.c | 2 +-
> drivers/of/of_private.h | 2 +-
> drivers/of/of_reserved_mem.c | 83 +++++++++++++++++++++---------------
> 3 files changed, 50 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 9cde2abd2fc0..ea2dff0478c7 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1239,7 +1239,7 @@ void __init unflatten_device_tree(void)
> unittest_unflatten_overlay_base();
>
> /* initialize the reserved memory regions */
> - of_init_reserved_mem();
> + of_scan_reserved_mem_reg_nodes();
> }
>
> /**
> diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
> index 01b33c4b1e9f..7412aed903df 100644
> --- a/drivers/of/of_private.h
> +++ b/drivers/of/of_private.h
> @@ -181,7 +181,7 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node *
> #endif
>
> int fdt_scan_reserved_mem(void);
> -void of_init_reserved_mem(void);
> +void of_scan_reserved_mem_reg_nodes(void);
>
> bool of_fdt_device_is_available(const void *blob, unsigned long node);
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index eb54490a0a11..b31001728866 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -97,6 +97,8 @@ static void __init alloc_reserved_mem_array(void)
> reserved_mem = new_array;
> }
>
> +static void __init of_init_reserved_mem_node(struct reserved_mem *rmem);
> +
> /*
> * of_reserved_mem_save_node() - save fdt node for second pass initialization
> */
> @@ -115,6 +117,12 @@ static void __init of_reserved_mem_save_node(struct device_node *node, const cha
> rmem->base = base;
> rmem->size = size;
>
> + /*
> + * Run the region specific initialization function for the rmem
> + * node.
> + */
> + of_init_reserved_mem_node(rmem);
> +
> reserved_mem_count++;
> return;
> }
> @@ -201,6 +209,8 @@ static int __init __fdt_reserved_mem_check_root(unsigned long node)
> return 0;
> }
>
> +static void __init __rmem_check_for_overlap(void);
> +
> /**
> * of_scan_reserved_mem_reg_nodes() - Store info for the "reg" defined
> * reserved memory regions.
> @@ -211,7 +221,7 @@ static int __init __fdt_reserved_mem_check_root(unsigned long node)
> * size are all stored in the reserved_mem array by calling the
> * of_reserved_mem_save_node() function.
> */
> -static void __init of_scan_reserved_mem_reg_nodes(void)
> +void __init of_scan_reserved_mem_reg_nodes(void)
> {
> struct device_node *node, *child;
> phys_addr_t base, size;
> @@ -222,6 +232,13 @@ static void __init of_scan_reserved_mem_reg_nodes(void)
> return;
> }
>
> + /*
> + * Before moving forward, allocate the exact size needed for the
> + * reserved_mem array and copy all previously saved contents
> + * into the new array if successful.
> + */
> + alloc_reserved_mem_array();
> +
> for_each_child_of_node(node, child) {
> int ret = 0;
> const char *uname;
> @@ -246,6 +263,8 @@ static void __init of_scan_reserved_mem_reg_nodes(void)
> if (size)
> of_reserved_mem_save_node(child, uname, base, size);
> }
> + /* check for overlapping reserved regions */
> + __rmem_check_for_overlap();
> }
>
> static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname);
> @@ -526,44 +545,38 @@ static void __init __rmem_check_for_overlap(void)
> }
>
> /**
> - * of_init_reserved_mem() - allocate and init all saved reserved memory regions
> + * of_init_reserved_mem_node() - Initialize a saved reserved memory region.
> + * @rmem: reserved_mem object of the memory region to be initialized.
> + *
> + * This function is used to call the region specific initialization
> + * function on the rmem object passed as an argument. The rmem object
> + * will contain the base address, size, node name, and device_node of
> + * the reserved memory region to be initialized.
> */
> -void __init of_init_reserved_mem(void)
> +static void __init of_init_reserved_mem_node(struct reserved_mem *rmem)
> {
> - int i;
> -
> - alloc_reserved_mem_array();
> -
> - of_scan_reserved_mem_reg_nodes();
> + int err;
> + bool nomap;
> + struct device_node *node = rmem->dev_node;
>
> - /* check for overlapping reserved regions */
> - __rmem_check_for_overlap();
> + nomap = of_property_present(node, "no-map");
>
> - for (i = 0; i < reserved_mem_count; i++) {
> - struct reserved_mem *rmem = &reserved_mem[i];
> - struct device_node *node = rmem->dev_node;
> - int err = 0;
> - bool nomap;
> -
> - nomap = of_property_present(node, "no-map");
> -
> - err = __reserved_mem_init_node(rmem);
> - if (err != 0 && err != -ENOENT) {
> - pr_info("node %s compatible matching fail\n", rmem->name);
> - if (nomap)
> - memblock_clear_nomap(rmem->base, rmem->size);
> - else
> - memblock_phys_free(rmem->base, rmem->size);
> - } else {
> - phys_addr_t end = rmem->base + rmem->size - 1;
> - bool reusable = of_property_present(node, "reusable");
> -
> - pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> - &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> - nomap ? "nomap" : "map",
> - reusable ? "reusable" : "non-reusable",
> - rmem->name ? rmem->name : "unknown");
> - }
> + err = __reserved_mem_init_node(rmem);
> + if (err != 0 && err != -ENOENT) {
> + pr_info("node %s compatible matching fail\n", rmem->name);
> + if (nomap)
> + memblock_clear_nomap(rmem->base, rmem->size);
> + else
> + memblock_phys_free(rmem->base, rmem->size);
> + } else {
> + phys_addr_t end = rmem->base + rmem->size - 1;
> + bool reusable = of_property_present(node, "reusable");
> +
> + pr_info("%pa..%pa (%lu KiB) %s %s %s\n",
> + &rmem->base, &end, (unsigned long)(rmem->size / SZ_1K),
> + nomap ? "nomap" : "map",
> + reusable ? "reusable" : "non-reusable",
> + rmem->name ? rmem->name : "unknown");
> }
> }
>
> --
> 2.34.1
>
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