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openwrt/target/linux/bcm27xx/patches-6.6/950-1349-cgroup-Use-kernel-command-line-to-disable-memory-cgr.patch
Álvaro Fernández Rojas 538a1d740c bcm27xx: update to latest RPi patches 
The patches were generated from the RPi repo with the following command:
git format-patch v6.6.58..rpi-6.6.y

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2024-10-31 13:44:23 +01:00

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From 86099deff5abf5f63643eecaedb4c11ae77474ce Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ma=C3=ADra=20Canal?= <mcanal@igalia.com>
Date: Thu, 24 Oct 2024 08:03:19 -0300
Subject: [PATCH 1349/1350] cgroup: Use kernel command line to disable memory
cgroup
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Commit 94a23e978235 ("cgroup: Disable cgroup "memory" by default")
disabled the memory cgroup by default when initing the cgroups. However,
it's possible to disable the memory cgroup by a kernel command line.
Hard-coding such a feature can be problematic as some memory management
features depend on the order that things are set.
For example, it is possible to see a NULL pointer dereference caused by
commit 94a23e978235cd35f38075072b34152b2b667e6e. The NULL pointer
dereference is triggered by the memory shrinker and ends up in a kernel
crash.
[ 50.028629] ==================================================================
[ 50.028645] BUG: KASAN: null-ptr-deref in do_shrink_slab+0x1fc/0x978
[ 50.028663] Write of size 8 at addr 0000000000000000 by task gfxrecon-replay/1965
[ 50.028676] CPU: 3 UID: 1000 PID: 1965 Comm: gfxrecon-replay Tainted: G C 6.12.0-rc4-v8-thp-kasan+ #85
[ 50.028685] Tainted: [C]=CRAP
[ 50.028689] Hardware name: Raspberry Pi 5 Model B Rev 1.0 (DT)
[ 50.028694] Call trace:
[ 50.028697] dump_backtrace+0xfc/0x120
[ 50.028706] show_stack+0x24/0x38
[ 50.028711] dump_stack_lvl+0x40/0x88
[ 50.028720] print_report+0xe4/0x708
[ 50.028728] kasan_report+0xcc/0x130
[ 50.028733] kasan_check_range+0x254/0x298
[ 50.028738] __kasan_check_write+0x20/0x30
[ 50.028745] do_shrink_slab+0x1fc/0x978
[ 50.028751] shrink_slab+0x318/0xc38
[ 50.028756] shrink_one+0x254/0x6d8
[ 50.028762] shrink_node+0x26b4/0x2848
[ 50.028767] do_try_to_free_pages+0x3e4/0x1190
[ 50.028773] try_to_free_pages+0x5a4/0xb40
[ 50.028778] __alloc_pages_direct_reclaim+0x144/0x298
[ 50.028787] __alloc_pages_slowpath+0x5c4/0xc70
[ 50.028793] __alloc_pages_noprof+0x4a8/0x6a8
[ 50.028800] __folio_alloc_noprof+0x24/0xa8
[ 50.028806] shmem_alloc_and_add_folio+0x2ec/0xce0
[ 50.028812] shmem_get_folio_gfp+0x380/0xc20
[ 50.028818] shmem_read_folio_gfp+0xe0/0x160
[ 50.028824] drm_gem_get_pages+0x238/0x620 [drm]
[ 50.029039] drm_gem_shmem_get_pages_sgt+0xd8/0x4b8 [drm_shmem_helper]
[ 50.029053] v3d_bo_create_finish+0x58/0x1e0 [v3d]
[ 50.029083] v3d_create_bo_ioctl+0xac/0x210 [v3d]
[ 50.029105] drm_ioctl_kernel+0x1d8/0x2b8 [drm]
[ 50.029220] drm_ioctl+0x4b4/0x920 [drm]
[ 50.029330] __arm64_sys_ioctl+0x11c/0x160
[ 50.029337] invoke_syscall+0x88/0x268
[ 50.029345] el0_svc_common+0x160/0x1d8
[ 50.029351] do_el0_svc+0x50/0x68
[ 50.029358] el0_svc+0x34/0x80
[ 50.029364] el0t_64_sync_handler+0x84/0x100
[ 50.029371] el0t_64_sync+0x190/0x198
[ 50.029376] ==================================================================
This happens because the memory shrinker is unaware that we are
artificially disabling the memory cgroups and therefore it doesn't
allocate `nr_deferred` (as it would if we used the kernel command line).
To avoid such an issue, revert the artificial disablement and disable it
through the command line. If a user wants to enable the feature, it can
use the `cgroup_enable=` command line.
Signed-off-by: Maíra Canal <mcanal@igalia.com>
---
arch/arm/boot/dts/broadcom/bcm2708-rpi-bt.dtsi | 2 +-
arch/arm/boot/dts/broadcom/bcm270x.dtsi | 2 +-
arch/arm/boot/dts/broadcom/bcm2711-rpi-cm4s.dts | 2 +-
arch/arm/boot/dts/broadcom/bcm2711-rpi-ds.dtsi | 2 +-
arch/arm/boot/dts/broadcom/bcm271x-rpi-bt.dtsi | 2 +-
arch/arm64/boot/dts/broadcom/bcm2712-rpi.dtsi | 2 +-
kernel/cgroup/cgroup.c | 15 +--------------
7 files changed, 7 insertions(+), 20 deletions(-)
--- a/arch/arm/boot/dts/broadcom/bcm2708-rpi-bt.dtsi
+++ b/arch/arm/boot/dts/broadcom/bcm2708-rpi-bt.dtsi
@@ -24,7 +24,7 @@
/ {
chosen {
- bootargs = "coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0";
+ bootargs = "coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0 cgroup_disable=memory";
};
aliases {
--- a/arch/arm/boot/dts/broadcom/bcm270x.dtsi
+++ b/arch/arm/boot/dts/broadcom/bcm270x.dtsi
@@ -4,7 +4,7 @@
/ {
chosen: chosen {
// Disable audio by default
- bootargs = "coherent_pool=1M snd_bcm2835.enable_headphones=0";
+ bootargs = "coherent_pool=1M snd_bcm2835.enable_headphones=0 cgroup_disable=memory";
stdout-path = "serial0:115200n8";
};
--- a/arch/arm/boot/dts/broadcom/bcm2711-rpi-cm4s.dts
+++ b/arch/arm/boot/dts/broadcom/bcm2711-rpi-cm4s.dts
@@ -148,7 +148,7 @@
/ {
chosen {
- bootargs = "coherent_pool=1M snd_bcm2835.enable_headphones=0 numa_policy=interleave";
+ bootargs = "coherent_pool=1M snd_bcm2835.enable_headphones=0 cgroup_disable=memory numa_policy=interleave";
};
aliases {
--- a/arch/arm/boot/dts/broadcom/bcm2711-rpi-ds.dtsi
+++ b/arch/arm/boot/dts/broadcom/bcm2711-rpi-ds.dtsi
@@ -3,7 +3,7 @@
/ {
chosen {
- bootargs = "coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0 numa_policy=interleave";
+ bootargs = "coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0 cgroup_disable=memory numa_policy=interleave";
};
__overrides__ {
--- a/arch/arm/boot/dts/broadcom/bcm271x-rpi-bt.dtsi
+++ b/arch/arm/boot/dts/broadcom/bcm271x-rpi-bt.dtsi
@@ -24,7 +24,7 @@
/ {
chosen {
- bootargs = "coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0";
+ bootargs = "coherent_pool=1M 8250.nr_uarts=1 snd_bcm2835.enable_headphones=0 cgroup_disable=memory";
};
aliases {
--- a/arch/arm64/boot/dts/broadcom/bcm2712-rpi.dtsi
+++ b/arch/arm64/boot/dts/broadcom/bcm2712-rpi.dtsi
@@ -99,7 +99,7 @@
/ {
chosen: chosen {
- bootargs = "reboot=w coherent_pool=1M 8250.nr_uarts=1 pci=pcie_bus_safe numa_policy=interleave iommu_dma_numa_policy=interleave system_heap.max_order=0";
+ bootargs = "reboot=w coherent_pool=1M 8250.nr_uarts=1 pci=pcie_bus_safe cgroup_disable=memory numa_policy=interleave iommu_dma_numa_policy=interleave system_heap.max_order=0";
stdout-path = "serial10:115200n8";
};
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -6060,9 +6060,6 @@ int __init cgroup_init_early(void)
return 0;
}
-static u16 cgroup_enable_mask __initdata;
-static int __init cgroup_disable(char *str);
-
/**
* cgroup_init - cgroup initialization
*
@@ -6096,12 +6093,6 @@ int __init cgroup_init(void)
cgroup_unlock();
- /*
- * Apply an implicit disable, knowing that an explicit enable will
- * prevent if from doing anything.
- */
- cgroup_disable("memory");
-
for_each_subsys(ss, ssid) {
if (ss->early_init) {
struct cgroup_subsys_state *css =
@@ -6742,10 +6733,6 @@ static int __init cgroup_disable(char *s
strcmp(token, ss->legacy_name))
continue;
- /* An explicit cgroup_enable overrides a disable */
- if (cgroup_enable_mask & (1 << i))
- continue;
-
static_branch_disable(cgroup_subsys_enabled_key[i]);
pr_info("Disabling %s control group subsystem\n",
ss->name);
@@ -6779,7 +6766,7 @@ static int __init cgroup_enable(char *st
strcmp(token, ss->legacy_name))
continue;
- cgroup_enable_mask |= 1 << i;
+ cgroup_feature_disable_mask &= ~(1 << i);
static_branch_enable(cgroup_subsys_enabled_key[i]);
pr_info("Enabling %s control group subsystem\n",
ss->name);
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