From: Jon Pan-Doh <pan...@google.com> Spammy devices can flood kernel logs with AER errors and slow/stall execution. Add per-device ratelimits for AER correctable and uncorrectable errors that use the kernel defaults (10 per 5s).
There are two AER logging entry points: - aer_print_error() is used by DPC and native AER - pci_print_aer() is used by GHES and CXL The native AER aer_print_error() case includes a loop that may log details from multiple devices. This is ratelimited by the union of ratelimits for these devices, set by add_error_device(), which collects the devices. If no such device is found, the Error Source message is ratelimited by the Root Port or RCEC that received the ERR_* message. The DPC aer_print_error() case is currently not ratelimited. The GHES and CXL pci_print_aer() cases are ratelimited by the Error Source device. Sargun at Meta reported internally that a flood of AER errors causes RCU CPU stall warnings and CSD-lock warnings. Tested using aer-inject[1]. Sent 11 AER errors. Observed 10 errors logged while AER stats (cat /sys/bus/pci/devices/<dev>/aer_dev_correctable) show true count of 11. [1] https://git.kernel.org/pub/scm/linux/kernel/git/gong.chen/aer-inject.git [bhelgaas: commit log, factor out trace_aer_event() and aer_print_rp_info() changes to previous patches, collect single aer_err_info.ratelimit as union of ratelimits of all error source devices] Link: https://lore.kernel.org/r/20250321015806.954866-7-pan...@google.com Reported-by: Sargun Dhillon <sar...@meta.com> Signed-off-by: Jon Pan-Doh <pan...@google.com> Signed-off-by: Bjorn Helgaas <bhelg...@google.com> --- drivers/pci/pci.h | 3 ++- drivers/pci/pcie/aer.c | 49 ++++++++++++++++++++++++++++++++++++------ drivers/pci/pcie/dpc.c | 1 + 3 files changed, 46 insertions(+), 7 deletions(-) diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h index 705f9ef58acc..65c466279ade 100644 --- a/drivers/pci/pci.h +++ b/drivers/pci/pci.h @@ -593,7 +593,8 @@ struct aer_err_info { unsigned int id:16; unsigned int severity:2; /* 0:NONFATAL | 1:FATAL | 2:COR */ - unsigned int __pad1:5; + unsigned int ratelimit:1; /* 0=skip, 1=print */ + unsigned int __pad1:4; unsigned int multi_error_valid:1; unsigned int first_error:5; diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c index da62032bf024..c335e0bb9f51 100644 --- a/drivers/pci/pcie/aer.c +++ b/drivers/pci/pcie/aer.c @@ -28,6 +28,7 @@ #include <linux/interrupt.h> #include <linux/delay.h> #include <linux/kfifo.h> +#include <linux/ratelimit.h> #include <linux/slab.h> #include <acpi/apei.h> #include <acpi/ghes.h> @@ -88,6 +89,10 @@ struct aer_report { u64 rootport_total_cor_errs; u64 rootport_total_fatal_errs; u64 rootport_total_nonfatal_errs; + + /* Ratelimits for errors */ + struct ratelimit_state cor_log_ratelimit; + struct ratelimit_state uncor_log_ratelimit; }; #define AER_LOG_TLP_MASKS (PCI_ERR_UNC_POISON_TLP| \ @@ -379,6 +384,11 @@ void pci_aer_init(struct pci_dev *dev) dev->aer_report = kzalloc(sizeof(*dev->aer_report), GFP_KERNEL); + ratelimit_state_init(&dev->aer_report->cor_log_ratelimit, + DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); + ratelimit_state_init(&dev->aer_report->uncor_log_ratelimit, + DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); + /* * We save/restore PCI_ERR_UNCOR_MASK, PCI_ERR_UNCOR_SEVER, * PCI_ERR_COR_MASK, and PCI_ERR_CAP. Root and Root Complex Event @@ -672,6 +682,18 @@ static void pci_rootport_aer_stats_incr(struct pci_dev *pdev, } } +static int aer_ratelimit(struct pci_dev *dev, unsigned int severity) +{ + struct ratelimit_state *ratelimit; + + if (severity == AER_CORRECTABLE) + ratelimit = &dev->aer_report->cor_log_ratelimit; + else + ratelimit = &dev->aer_report->uncor_log_ratelimit; + + return __ratelimit(ratelimit); +} + static void __aer_print_error(struct pci_dev *dev, struct aer_err_info *info) { const char **strings; @@ -715,6 +737,9 @@ void aer_print_error(struct pci_dev *dev, struct aer_err_info *info) pci_dev_aer_stats_incr(dev, info); + if (!info->ratelimit) + return; + if (!info->status) { pci_err(dev, "PCIe Bus Error: severity=%s, type=Inaccessible, (Unregistered Agent ID)\n", aer_error_severity_string[info->severity]); @@ -785,6 +810,9 @@ void pci_print_aer(struct pci_dev *dev, int aer_severity, pci_dev_aer_stats_incr(dev, &info); + if (!aer_ratelimit(dev, info.severity)) + return; + layer = AER_GET_LAYER_ERROR(aer_severity, status); agent = AER_GET_AGENT(aer_severity, status); @@ -815,8 +843,14 @@ EXPORT_SYMBOL_NS_GPL(pci_print_aer, "CXL"); */ static int add_error_device(struct aer_err_info *e_info, struct pci_dev *dev) { + /* + * Ratelimit AER log messages. Generally we add the Error Source + * device, but there are is_error_source() cases that can result in + * multiple devices being added here, so we OR them all together. + */ if (e_info->error_dev_num < AER_MAX_MULTI_ERR_DEVICES) { e_info->dev[e_info->error_dev_num] = pci_dev_get(dev); + e_info->ratelimit |= aer_ratelimit(dev, e_info->severity); e_info->error_dev_num++; return 0; } @@ -914,7 +948,7 @@ static int find_device_iter(struct pci_dev *dev, void *data) * e_info->error_dev_num and e_info->dev[], based on the given information. */ static bool find_source_device(struct pci_dev *parent, - struct aer_err_info *e_info) + struct aer_err_info *e_info) { struct pci_dev *dev = parent; int result; @@ -935,10 +969,12 @@ static bool find_source_device(struct pci_dev *parent, /* * If we didn't find any devices with errors logged in the AER * Capability, just print the Error Source ID from the Root Port or - * RCEC that received an ERR_* Message. + * RCEC that received an ERR_* Message, ratelimited by the RP or + * RCEC. */ if (!e_info->error_dev_num) { - aer_print_source(parent, e_info, " (no details found)"); + if (aer_ratelimit(parent, e_info->severity)) + aer_print_source(parent, e_info, " (no details found)"); return false; } return true; @@ -1147,9 +1183,10 @@ static void aer_recover_work_func(struct work_struct *work) pdev = pci_get_domain_bus_and_slot(entry.domain, entry.bus, entry.devfn); if (!pdev) { - pr_err("no pci_dev for %04x:%02x:%02x.%x\n", - entry.domain, entry.bus, - PCI_SLOT(entry.devfn), PCI_FUNC(entry.devfn)); + pr_err_ratelimited("%04x:%02x:%02x.%x: no pci_dev found\n", + entry.domain, entry.bus, + PCI_SLOT(entry.devfn), + PCI_FUNC(entry.devfn)); continue; } pci_print_aer(pdev, entry.severity, entry.regs); diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c index 34af0ea45c0d..597df7790f36 100644 --- a/drivers/pci/pcie/dpc.c +++ b/drivers/pci/pcie/dpc.c @@ -301,6 +301,7 @@ void dpc_process_error(struct pci_dev *pdev) else if (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_UNCOR && dpc_get_aer_uncorrect_severity(pdev, &info) && aer_get_device_error_info(pdev, &info)) { + info.ratelimit = 1; /* no ratelimiting */ aer_print_error(pdev, &info); pci_aer_clear_nonfatal_status(pdev); pci_aer_clear_fatal_status(pdev); -- 2.43.0
