- Linux-stable-mirror - lists.linaro.org

FAILED: patch "[PATCH] drm/sched: Fix race in drm_sched_entity_select_rq()" failed to apply to 6.12-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 6.12-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.12.y git checkout FETCH_HEAD git cherry-pick -x d25e3a610bae03bffc5c14b5d944a5d0cd844678 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable(a)vger.kernel.org>' --in-reply-to '2025110342-exhume-mankind-5952@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ From d25e3a610bae03bffc5c14b5d944a5d0cd844678 Mon Sep 17 00:00:00 2001 From: Philipp Stanner <phasta(a)kernel.org> Date: Wed, 22 Oct 2025 08:34:03 +0200 Subject: [PATCH] drm/sched: Fix race in drm_sched_entity_select_rq() In a past bug fix it was forgotten that entity access must be protected by the entity lock. That's a data race and potentially UB. Move the spin_unlock() to the appropriate position. Cc: stable(a)vger.kernel.org # v5.13+ Fixes: ac4eb83ab255 ("drm/sched: select new rq even if there is only one v3") Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin(a)igalia.com> Signed-off-by: Philipp Stanner <phasta(a)kernel.org> Link: https://patch.msgid.link/20251022063402.87318-2-phasta@kernel.org diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 5a4697f636f2..aa222166de58 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -552,10 +552,11 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity) drm_sched_rq_remove_entity(entity->rq, entity); entity->rq = rq; } - spin_unlock(&entity->lock); if (entity->num_sched_list == 1) entity->sched_list = NULL; + + spin_unlock(&entity->lock); } /**

1 month

2
3
0 0

[PATCH net v3 1/3] net,mptcp: fix proto fallback detection with BPF sockmap

by Jiayuan Chen

When the server has MPTCP enabled but receives a non-MP-capable request from a client, it calls mptcp_fallback_tcp_ops(). Since non-MPTCP connections are allowed to use sockmap, which replaces sk->sk_prot, using sk->sk_prot to determine the IP version in mptcp_fallback_tcp_ops() becomes unreliable. This can lead to assigning incorrect ops to sk->sk_socket->ops. Additionally, when BPF Sockmap modifies the protocol handlers, the original WARN_ON_ONCE(sk->sk_prot != &tcp_prot) check would falsely trigger warnings. Fix this by using the more stable sk_family to distinguish between IPv4 and IPv6 connections, ensuring correct fallback protocol operations are selected even when BPF Sockmap has modified the socket protocol handlers. Fixes: 0b4f33def7bb ("mptcp: fix tcp fallback crash") Cc: <stable(a)vger.kernel.org> Signed-off-by: Jiayuan Chen <jiayuan.chen(a)linux.dev> Reviewed-by: Jakub Sitnicki <jakub(a)cloudflare.com> --- net/mptcp/protocol.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 0292162a14ee..2393741bc310 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -61,11 +61,16 @@ static u64 mptcp_wnd_end(const struct mptcp_sock *msk) static const struct proto_ops *mptcp_fallback_tcp_ops(const struct sock *sk) { + /* When BPF sockmap is used, it may replace sk->sk_prot. + * Using sk_family is a reliable way to determine the IP version. + */ + unsigned short family = READ_ONCE(sk->sk_family); + #if IS_ENABLED(CONFIG_MPTCP_IPV6) - if (sk->sk_prot == &tcpv6_prot) + if (family == AF_INET6) return &inet6_stream_ops; #endif - WARN_ON_ONCE(sk->sk_prot != &tcp_prot); + WARN_ON_ONCE(family != AF_INET); return &inet_stream_ops; } -- 2.43.0

1 month

3
6
0 0

[tip: x86/urgent] x86/amd_node: Fix AMD root device caching

by tip-bot2 for Yazen Ghannam

The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 0a4b61d9c2e496b5f0a10e29e355a1465c8738bb Gitweb: https://git.kernel.org/tip/0a4b61d9c2e496b5f0a10e29e355a1465c8738bb Author: Yazen Ghannam <yazen.ghannam(a)amd.com> AuthorDate: Tue, 28 Oct 2025 21:35:42 Committer: Borislav Petkov (AMD) <bp(a)alien8.de> CommitterDate: Mon, 03 Nov 2025 12:46:57 +01:00 x86/amd_node: Fix AMD root device caching Recent AMD node rework removed the "search and count" method of caching AMD root devices. This depended on the value from a Data Fabric register that was expected to hold the PCI bus of one of the root devices attached to that fabric. However, this expectation is incorrect. The register, when read from PCI config space, returns the bitwise-OR of the buses of all attached root devices. This behavior is benign on AMD reference design boards, since the bus numbers are aligned. This results in a bitwise-OR value matching one of the buses. For example, 0x00 | 0x40 | 0xA0 | 0xE0 = 0xE0. This behavior breaks on boards where the bus numbers are not exactly aligned. For example, 0x00 | 0x07 | 0xE0 | 0x15 = 0x1F. The examples above are for AMD node 0. The first root device on other nodes will not be 0x00. The first root device for other nodes will depend on the total number of root devices, the system topology, and the specific PCI bus number assignment. For example, a system with 2 AMD nodes could have this: Node 0 : 0x00 0x07 0x0e 0x15 Node 1 : 0x1c 0x23 0x2a 0x31 The bus numbering style in the reference boards is not a requirement. The numbering found in other boards is not incorrect. Therefore, the root device caching method needs to be adjusted. Go back to the "search and count" method used before the recent rework. Search for root devices using PCI class code rather than fixed PCI IDs. This keeps the goal of the rework (remove dependency on PCI IDs) while being able to support various board designs. Merge helper functions to reduce code duplication. [ bp: Reflow comment. ] Fixes: 40a5f6ffdfc8 ("x86/amd_nb: Simplify root device search") Signed-off-by: Yazen Ghannam <yazen.ghannam(a)amd.com> Signed-off-by: Borislav Petkov (AMD) <bp(a)alien8.de> Cc: stable(a)vger.kernel.org Link: https://patch.msgid.link/all/20251028-fix-amd-root-v2-1-843e38f8be2c@amd.com --- arch/x86/include/asm/amd/node.h | 1 +- arch/x86/kernel/amd_node.c | 150 ++++++++++--------------------- 2 files changed, 51 insertions(+), 100 deletions(-) diff --git a/arch/x86/include/asm/amd/node.h b/arch/x86/include/asm/amd/node.h index 23fe617..a672b87 100644 --- a/arch/x86/include/asm/amd/node.h +++ b/arch/x86/include/asm/amd/node.h @@ -23,7 +23,6 @@ #define AMD_NODE0_PCI_SLOT 0x18 struct pci_dev *amd_node_get_func(u16 node, u8 func); -struct pci_dev *amd_node_get_root(u16 node); static inline u16 amd_num_nodes(void) { diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c index a40176b..3d0a476 100644 --- a/arch/x86/kernel/amd_node.c +++ b/arch/x86/kernel/amd_node.c @@ -34,62 +34,6 @@ struct pci_dev *amd_node_get_func(u16 node, u8 func) return pci_get_domain_bus_and_slot(0, 0, PCI_DEVFN(AMD_NODE0_PCI_SLOT + node, func)); } -#define DF_BLK_INST_CNT 0x040 -#define DF_CFG_ADDR_CNTL_LEGACY 0x084 -#define DF_CFG_ADDR_CNTL_DF4 0xC04 - -#define DF_MAJOR_REVISION GENMASK(27, 24) - -static u16 get_cfg_addr_cntl_offset(struct pci_dev *df_f0) -{ - u32 reg; - - /* - * Revision fields added for DF4 and later. - * - * Major revision of '0' is found pre-DF4. Field is Read-as-Zero. - */ - if (pci_read_config_dword(df_f0, DF_BLK_INST_CNT, &reg)) - return 0; - - if (reg & DF_MAJOR_REVISION) - return DF_CFG_ADDR_CNTL_DF4; - - return DF_CFG_ADDR_CNTL_LEGACY; -} - -struct pci_dev *amd_node_get_root(u16 node) -{ - struct pci_dev *root; - u16 cntl_off; - u8 bus; - - if (!cpu_feature_enabled(X86_FEATURE_ZEN)) - return NULL; - - /* - * D18F0xXXX [Config Address Control] (DF::CfgAddressCntl) - * Bits [7:0] (SecBusNum) holds the bus number of the root device for - * this Data Fabric instance. The segment, device, and function will be 0. - */ - struct pci_dev *df_f0 __free(pci_dev_put) = amd_node_get_func(node, 0); - if (!df_f0) - return NULL; - - cntl_off = get_cfg_addr_cntl_offset(df_f0); - if (!cntl_off) - return NULL; - - if (pci_read_config_byte(df_f0, cntl_off, &bus)) - return NULL; - - /* Grab the pointer for the actual root device instance. */ - root = pci_get_domain_bus_and_slot(0, bus, 0); - - pci_dbg(root, "is root for AMD node %u\n", node); - return root; -} - static struct pci_dev **amd_roots; /* Protect the PCI config register pairs used for SMN. */ @@ -274,51 +218,21 @@ DEFINE_SHOW_STORE_ATTRIBUTE(smn_node); DEFINE_SHOW_STORE_ATTRIBUTE(smn_address); DEFINE_SHOW_STORE_ATTRIBUTE(smn_value); -static int amd_cache_roots(void) -{ - u16 node, num_nodes = amd_num_nodes(); - - amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL); - if (!amd_roots) - return -ENOMEM; - - for (node = 0; node < num_nodes; node++) - amd_roots[node] = amd_node_get_root(node); - - return 0; -} - -static int reserve_root_config_spaces(void) +static struct pci_dev *get_next_root(struct pci_dev *root) { - struct pci_dev *root = NULL; - struct pci_bus *bus = NULL; - - while ((bus = pci_find_next_bus(bus))) { - /* Root device is Device 0 Function 0 on each Primary Bus. */ - root = pci_get_slot(bus, 0); - if (!root) + while ((root = pci_get_class(PCI_CLASS_BRIDGE_HOST << 8, root))) { + /* Root device is Device 0 Function 0. */ + if (root->devfn) continue; if (root->vendor != PCI_VENDOR_ID_AMD && root->vendor != PCI_VENDOR_ID_HYGON) continue; - pci_dbg(root, "Reserving PCI config space\n"); - - /* - * There are a few SMN index/data pairs and other registers - * that shouldn't be accessed by user space. - * So reserve the entire PCI config space for simplicity rather - * than covering specific registers piecemeal. - */ - if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) { - pci_err(root, "Failed to reserve config space\n"); - return -EEXIST; - } + break; } - smn_exclusive = true; - return 0; + return root; } static bool enable_dfs; @@ -332,7 +246,8 @@ __setup("amd_smn_debugfs_enable", amd_smn_enable_dfs); static int __init amd_smn_init(void) { - int err; + u16 count, num_roots, roots_per_node, node, num_nodes; + struct pci_dev *root; if (!cpu_feature_enabled(X86_FEATURE_ZEN)) return 0; @@ -342,13 +257,48 @@ static int __init amd_smn_init(void) if (amd_roots) return 0; - err = amd_cache_roots(); - if (err) - return err; + num_roots = 0; + root = NULL; + while ((root = get_next_root(root))) { + pci_dbg(root, "Reserving PCI config space\n"); - err = reserve_root_config_spaces(); - if (err) - return err; + /* + * There are a few SMN index/data pairs and other registers + * that shouldn't be accessed by user space. So reserve the + * entire PCI config space for simplicity rather than covering + * specific registers piecemeal. + */ + if (!pci_request_config_region_exclusive(root, 0, PCI_CFG_SPACE_SIZE, NULL)) { + pci_err(root, "Failed to reserve config space\n"); + return -EEXIST; + } + + num_roots++; + } + + pr_debug("Found %d AMD root devices\n", num_roots); + + if (!num_roots) + return -ENODEV; + + num_nodes = amd_num_nodes(); + amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL); + if (!amd_roots) + return -ENOMEM; + + roots_per_node = num_roots / num_nodes; + + count = 0; + node = 0; + root = NULL; + while (node < num_nodes && (root = get_next_root(root))) { + /* Use one root for each node and skip the rest. */ + if (count++ % roots_per_node) + continue; + + pci_dbg(root, "is root for AMD node %u\n", node); + amd_roots[node++] = root; + } if (enable_dfs) { debugfs_dir = debugfs_create_dir("amd_smn", arch_debugfs_dir); @@ -358,6 +308,8 @@ static int __init amd_smn_init(void) debugfs_create_file("value", 0600, debugfs_dir, NULL, &smn_value_fops); } + smn_exclusive = true; + return 0; }

1 month

1
0
0 0

[PATCH] usb: xhci: Check kcalloc_node() when allocating interrupter array in xhci_mem_init()

by Guangshuo Li

kcalloc_node() may fail. When the interrupter array allocation returns NULL, subsequent code uses xhci->interrupters (e.g. in xhci_add_interrupter() and in cleanup paths), leading to a potential NULL pointer dereference. Check the allocation and bail out to the existing fail path to avoid the NULL dereference. Fixes: c99b38c412343 ("xhci: add support to allocate several interrupters") Cc: stable(a)vger.kernel.org Signed-off-by: Guangshuo Li <lgs201920130244(a)gmail.com> --- drivers/usb/host/xhci-mem.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c index d698095fc88d..da257856e864 100644 --- a/drivers/usb/host/xhci-mem.c +++ b/drivers/usb/host/xhci-mem.c @@ -2505,7 +2505,8 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags) "Allocating primary event ring"); xhci->interrupters = kcalloc_node(xhci->max_interrupters, sizeof(*xhci->interrupters), flags, dev_to_node(dev)); - + if (!xhci->interrupters) + goto fail; ir = xhci_alloc_interrupter(xhci, 0, flags); if (!ir) goto fail; -- 2.43.0

1 month

4
5
0 0

[PATCH] phy: Fix error handling in tegra_xusb_pad_init

by Ma Ke

If device_add() fails, do not use device_unregister() for error handling. device_unregister() consists two functions: device_del() and put_device(). device_unregister() should only be called after device_add() succeeded because device_del() undoes what device_add() does if successful. Change device_unregister() to put_device() call before returning from the function. As comment of device_add() says, 'if device_add() succeeds, you should call device_del() when you want to get rid of it. If device_add() has not succeeded, use only put_device() to drop the reference count'. Found by code review. Cc: stable(a)vger.kernel.org Fixes: 78876f71b3e9 ("media: pci: intel: ivsc: Add ACE submodule") Signed-off-by: Ma Ke <make24(a)iscas.ac.cn> --- drivers/phy/tegra/xusb.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/phy/tegra/xusb.c b/drivers/phy/tegra/xusb.c index c89df95aa6ca..d89493d68699 100644 --- a/drivers/phy/tegra/xusb.c +++ b/drivers/phy/tegra/xusb.c @@ -171,16 +171,16 @@ int tegra_xusb_pad_init(struct tegra_xusb_pad *pad, err = dev_set_name(&pad->dev, "%s", pad->soc->name); if (err < 0) - goto unregister; + goto put_device; err = device_add(&pad->dev); if (err < 0) - goto unregister; + goto put_device; return 0; -unregister: - device_unregister(&pad->dev); +put_device: + put_device(&pad->dev); return err; } -- 2.17.1

1 month

2
1
0 0

[PATCH] media: renesas: rcar_drif: fix device node reference leak in rcar_drif_bond_enabled

by Miaoqian Lin

The function calls of_parse_phandle() which returns a device node with an incremented reference count. When the bonded device is not available, the function returns NULL without releasing the reference, causing a reference leak. Add of_node_put(np) to release the device node reference. The of_node_put function handles NULL pointers. Found through static analysis by reviewing the doc of of_parse_phandle() and cross-checking its usage patterns across the codebase. Fixes: 7625ee981af1 ("[media] media: platform: rcar_drif: Add DRIF support") Cc: stable(a)vger.kernel.org Signed-off-by: Miaoqian Lin <linmq006(a)gmail.com> --- drivers/media/platform/renesas/rcar_drif.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/media/platform/renesas/rcar_drif.c b/drivers/media/platform/renesas/rcar_drif.c index fc8b6bbef793..c5d676eb1091 100644 --- a/drivers/media/platform/renesas/rcar_drif.c +++ b/drivers/media/platform/renesas/rcar_drif.c @@ -1246,6 +1246,7 @@ static struct device_node *rcar_drif_bond_enabled(struct platform_device *p) if (np && of_device_is_available(np)) return np; + of_node_put(np); return NULL; } -- 2.35.1

1 month

5
4
0 0

Payment for Inv-1022

by Bergtrade®

1 month

1
0
0 0

[tip: perf/urgent] perf/core: Fix system hang caused by cpu-clock usage

by tip-bot2 for Dapeng Mi

The following commit has been merged into the perf/urgent branch of tip: Commit-ID: eb3182ef0405ff2f6668fd3e5ff9883f60ce8801 Gitweb: https://git.kernel.org/tip/eb3182ef0405ff2f6668fd3e5ff9883f60ce8801 Author: Dapeng Mi <dapeng1.mi(a)linux.intel.com> AuthorDate: Wed, 15 Oct 2025 13:18:28 +08:00 Committer: Ingo Molnar <mingo(a)kernel.org> CommitterDate: Mon, 03 Nov 2025 11:04:19 +01:00 perf/core: Fix system hang caused by cpu-clock usage cpu-clock usage by the async-profiler tool can trigger a system hang, which got bisected back to the following commit by Octavia Togami: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") causes this issue The root cause of the hang is that cpu-clock is a special type of SW event which relies on hrtimers. The __perf_event_overflow() callback is invoked from the hrtimer handler for cpu-clock events, and __perf_event_overflow() tries to call cpu_clock_event_stop() to stop the event, which calls htimer_cancel() to cancel the hrtimer. But that's a recursion into the hrtimer code from a hrtimer handler, which (unsurprisingly) deadlocks. To fix this bug, use hrtimer_try_to_cancel() instead, and set the PERF_HES_STOPPED flag, which causes perf_swevent_hrtimer() to stop the event once it sees the PERF_HES_STOPPED flag. [ mingo: Fixed the comments and improved the changelog. ] Closes: https://lore.kernel.org/all/CAHPNGSQpXEopYreir+uDDEbtXTBvBvi8c6fYXJvceqtgTP… Fixes: 18dbcbfabfff ("perf: Fix the POLL_HUP delivery breakage") Reported-by: Octavia Togami <octavia.togami(a)gmail.com> Suggested-by: Peter Zijlstra <peterz(a)infradead.org> Signed-off-by: Dapeng Mi <dapeng1.mi(a)linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz(a)infradead.org> Signed-off-by: Ingo Molnar <mingo(a)kernel.org> Tested-by: Octavia Togami <octavia.togami(a)gmail.com> Cc: stable(a)vger.kernel.org Link: https://github.com/lucko/spark/issues/530 Link: https://patch.msgid.link/20251015051828.12809-1-dapeng1.mi@linux.intel.com --- kernel/events/core.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 177e57c..1fd347d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11773,7 +11773,8 @@ static enum hrtimer_restart perf_swevent_hrtimer(struct hrtimer *hrtimer) event = container_of(hrtimer, struct perf_event, hw.hrtimer); - if (event->state != PERF_EVENT_STATE_ACTIVE) + if (event->state != PERF_EVENT_STATE_ACTIVE || + event->hw.state & PERF_HES_STOPPED) return HRTIMER_NORESTART; event->pmu->read(event); @@ -11819,15 +11820,20 @@ static void perf_swevent_cancel_hrtimer(struct perf_event *event) struct hw_perf_event *hwc = &event->hw; /* - * The throttle can be triggered in the hrtimer handler. - * The HRTIMER_NORESTART should be used to stop the timer, - * rather than hrtimer_cancel(). See perf_swevent_hrtimer() + * Careful: this function can be triggered in the hrtimer handler, + * for cpu-clock events, so hrtimer_cancel() would cause a + * deadlock. + * + * So use hrtimer_try_to_cancel() to try to stop the hrtimer, + * and the cpu-clock handler also sets the PERF_HES_STOPPED flag, + * which guarantees that perf_swevent_hrtimer() will stop the + * hrtimer once it sees the PERF_HES_STOPPED flag. */ if (is_sampling_event(event) && (hwc->interrupts != MAX_INTERRUPTS)) { ktime_t remaining = hrtimer_get_remaining(&hwc->hrtimer); local64_set(&hwc->period_left, ktime_to_ns(remaining)); - hrtimer_cancel(&hwc->hrtimer); + hrtimer_try_to_cancel(&hwc->hrtimer); } } @@ -11871,12 +11877,14 @@ static void cpu_clock_event_update(struct perf_event *event) static void cpu_clock_event_start(struct perf_event *event, int flags) { + event->hw.state = 0; local64_set(&event->hw.prev_count, local_clock()); perf_swevent_start_hrtimer(event); } static void cpu_clock_event_stop(struct perf_event *event, int flags) { + event->hw.state = PERF_HES_STOPPED; perf_swevent_cancel_hrtimer(event); if (flags & PERF_EF_UPDATE) cpu_clock_event_update(event); @@ -11950,12 +11958,14 @@ static void task_clock_event_update(struct perf_event *event, u64 now) static void task_clock_event_start(struct perf_event *event, int flags) { + event->hw.state = 0; local64_set(&event->hw.prev_count, event->ctx->time); perf_swevent_start_hrtimer(event); } static void task_clock_event_stop(struct perf_event *event, int flags) { + event->hw.state = PERF_HES_STOPPED; perf_swevent_cancel_hrtimer(event); if (flags & PERF_EF_UPDATE) task_clock_event_update(event, event->ctx->time);

1 month

1
0
0 0

Re: [REGRESSION] bisected: perf: hang when using async-profiler caused by perf: Fix the POLL_HUP delivery breakage

by Harvey Tite

Hello hope everyone is well, just following up on this bug report, this appears to have been patched here https://lore.kernel.org/lkml/20251015051828.12809-1-dapeng1.mi@linux.intel.… thanks to Dapeng Mi; however, the patch email does not appear to have CCed the regressions or stable list. On 2025/10/15 Peter Zijlstra wrote: > So yeah, I suppose this works. Let me go queue this up. In regard to the patch, hence I assume the patch is approved for implementation in future versions. This is a critical bug causing widespread irrecoverable system freezes reported by many users with many differing setups, including myself. Notably it is being triggered by a minecraft mod called spark with at least 150 million aggregate downloads (https://www.curseforge.com/minecraft/mc-mods/spark https://github.com/lucko/spark/issues/530). If at all possible I would love to request that this please be implemented/backported to kernels 6.17 and 6.18. Thank you.

1 month

2
1
0 0

[PATCH 6.6.y 0/7] mm: memcg: subtree stats flushing and thresholds

by Leon Huang Fu

We observed failures in the 'memcontrol02' test case from the Linux Test Project (LTP) [1] when running on a 256-core server with the 6.6.y kernel. The test fails due to stale memory.stat values being returned, which is caused by the current stats flushing implementation's limitations with large core counts. This series backports the memcg subtree stats flushing improvements from Linux 6.8 to 6.6.y to address the issue. The main goal is to restore per-memcg stats flushing with dynamic thresholds, which improves both accuracy and performance of memory cgroup statistics, especially on high-core-count systems. Background ========== The current stats flushing in 6.6.y flushes the entire memcg hierarchy with a global threshold. This is not efficient and can cause stale stats when read 'memory.stat'. Dependency Patches ================== Patches 1-2 are dependencies required for clean application of the main series: Patch 1: 811244a501b9 "mm: memcg: add THP swap out info for anonymous reclaim" This patch adds THP_SWPOUT and THP_SWPOUT_FALLBACK entries to the memcg_vm_event_stat[] array. It is needed because patch 4 (e0bf1dc859fd) moves the vmstats struct definitions, including this array. Without this patch, the array structure would not match between 6.6.y and 6.8, causing context conflicts during cherry-pick. The patch is already in mainline (merged in v6.7) but was not included in the stable 6.6.y branch. Patch 2: 7108cc3f765c "mm: memcg: add per-memcg zswap writeback stat" This patch adds the ZSWPWB entry to the memcg_vm_event_stat[] array. Like patch 1, it is required for patch 4 to apply cleanly. The array structure must match the 6.8 state for the code movement to succeed without conflicts. This patch is also in mainline (merged in v6.8) but was not backported to 6.6.y. Main Series =========== Patches 3-7 are the core memcg stats flushing improvements: - Patch 3: Renames flush_next_time to flush_last_time for clarity - Patch 4: Moves vmstats struct definitions for better code organization - Patch 5: Implements per-memcg stats flushing thresholds (key change) - Patch 6: Moves stats flush into workingset_test_recent() - Patch 7: Restores subtree stats flushing (main feature) Cherry-Pick Notes for Patch 7 ============================== Patch 7 (7d7ef0a4686a) requires manual conflict resolution in mm/zswap.c: The conflict occurs because this patch includes changes to zswap shrinker code that was introduced in Linux 6.8. Since this new shrinker infrastructure does not exist in 6.6.y, the conflicting code should be removed during cherry-pick. Resolution: Keep the 6.6.y (HEAD) version of mm/zswap.c and discard the new shrinker code from the patch. The conflict markers will show: <<<<<<< HEAD // existing 6.6.y code ======= // new 6.8 shrinker code (shrink_memcg_cb, zswap_shrinker_scan, etc.) >>>>>>> 7d7ef0a4686a Simply keep the HEAD version and remove everything between the "=======" and ">>>>>>>" markers. This is safe because the zswap shrinker is a separate new feature, not a dependency for the memcg stats changes. Additionally, if you encounter a conflict in mm/workingset.c, it may be due to commit 417dbd7be383 ("mm: ratelimit stat flush from workingset shrinker") which was backported to 6.6.y. The resolution is to use: mem_cgroup_flush_stats_ratelimited(sc->memcg) which preserves the performance optimization while using the new API. Testing ======= This series has been extensively tested upstream with: - 5000 concurrent workers in 500 cgroups doing allocations and reclaim - 250k threads reading stats every 100ms in 50k cgroups - No performance regressions observed with per-memcg thresholds The changes improve both stats accuracy and reduce unnecessary flushing overhead. References ========== [1] Linux Test Project (LTP): https://github.com/linux-test-project/ltp Domenico Cerasuolo (1): mm: memcg: add per-memcg zswap writeback stat Xin Hao (1): mm: memcg: add THP swap out info for anonymous reclaim Yosry Ahmed (5): mm: memcg: change flush_next_time to flush_last_time mm: memcg: move vmstats structs definition above flushing code mm: memcg: make stats flushing threshold per-memcg mm: workingset: move the stats flush into workingset_test_recent() mm: memcg: restore subtree stats flushing Documentation/admin-guide/cgroup-v2.rst | 9 + include/linux/memcontrol.h | 8 +- include/linux/vm_event_item.h | 1 + mm/memcontrol.c | 266 +++++++++++++----------- mm/page_io.c | 8 +- mm/vmscan.c | 3 +- mm/vmstat.c | 1 + mm/workingset.c | 42 ++-- mm/zswap.c | 4 + 9 files changed, 203 insertions(+), 139 deletions(-) -- 2.50.1

1 month

1
7
0 0

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-stable-mirror