* [PATCH v5 01/10] fs/resctrl: Use correct format specifier for printing error pointers
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 02/10] x86/resctrl: Protect against bad shift Reinette Chatre
` (10 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
Use correct format specifier for error pointer as coccinelle suggests:
.../fs/resctrl/monitor.c:148:8-15: WARNING: Consider using %pe to print PTR_ERR()
.../fs/resctrl/monitor.c:760:9-16: WARNING: Consider using %pe to print PTR_ERR()
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v4:
- Add Tony's Reviewed-by tag.
---
fs/resctrl/monitor.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 7340b1d17f17..29b13a690cf3 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -144,8 +144,8 @@ void __check_limbo(struct rdt_l3_mon_domain *d, bool force_free)
arch_priv = mon_event_all[QOS_L3_OCCUP_EVENT_ID].arch_priv;
arch_mon_ctx = resctrl_arch_mon_ctx_alloc(r, QOS_L3_OCCUP_EVENT_ID);
if (IS_ERR(arch_mon_ctx)) {
- pr_warn_ratelimited("Failed to allocate monitor context: %ld",
- PTR_ERR(arch_mon_ctx));
+ pr_warn_ratelimited("Failed to allocate monitor context: %pe",
+ arch_mon_ctx);
return;
}
@@ -771,8 +771,8 @@ static void mbm_update_one_event(struct rdt_resource *r, struct rdt_l3_mon_domai
} else {
rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, evtid);
if (IS_ERR(rr.arch_mon_ctx)) {
- pr_warn_ratelimited("Failed to allocate monitor context: %ld",
- PTR_ERR(rr.arch_mon_ctx));
+ pr_warn_ratelimited("Failed to allocate monitor context: %pe",
+ rr.arch_mon_ctx);
return;
}
}
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 02/10] x86/resctrl: Protect against bad shift
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 01/10] fs/resctrl: Use correct format specifier for printing error pointers Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 03/10] fs/resctrl: Change pattern used to track number of entries in enum Reinette Chatre
` (9 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
The size of the bandwidth specifier field is enumerated from AMD hardware.
resctrl uses this field width to determine the maximum bandwidth supported
that is stored in resctrl_membw::max_bw to which user space allocation
requests are compared for validity.
resctrl_membw::max_bw is of type u32 while the register containing the
bandwidth specifier field, L3QOS_BW_CONTROL_n, is 64 bits. While not an
issue with current hardware it is theoretically possible that enumeration
of maximum bandwidth may trigger invalid behavior if a future system can
use a bandwidth specifier field larger than 32 bits. Whether this could
ever represent a reasonable bandwidth value is unknown but addressing the
issue will appease static checkers.
Ensure resctrl can accommodate the hardware's bandwidth specifier field
width with an additional check. Switch to BIT() instead of open-coding the
bitshift to avoid signed integer overflow if the number of bits is a
valid 31.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v3:
- Use pr_warn() instead of WARN_ON().
sashiko: https://sashiko.dev/#/patchset/cover.1775576382.git.reinette.chatre%40intel.com
Changes since v4:
- Add Tony's Reviewed-by tag.
---
arch/x86/kernel/cpu/resctrl/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index bca782050198..9b9495174041 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -247,7 +247,11 @@ static __init bool __rdt_get_mem_config_amd(struct rdt_resource *r)
cpuid_count(0x80000020, subleaf, &eax, &ebx, &ecx, &edx);
hw_res->num_closid = edx + 1;
- r->membw.max_bw = 1 << eax;
+ if (BITS_PER_TYPE(r->membw.max_bw) <= eax) {
+ pr_warn("Unable to support hardware's maximum bandwidth\n");
+ return false;
+ }
+ r->membw.max_bw = BIT(eax);
/* AMD does not use delay */
r->membw.delay_linear = false;
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 03/10] fs/resctrl: Change pattern used to track number of entries in enum
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 01/10] fs/resctrl: Use correct format specifier for printing error pointers Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 02/10] x86/resctrl: Protect against bad shift Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 04/10] fs/resctrl: Use accurate type for rdt_resource::rid Reinette Chatre
` (8 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
CDP_NUM_TYPES tracks the number of different configuration types that can
be applied to a resource. CDP_NUM_TYPES is required to iterate over the
different configurations but is not a member of enum resctrl_conf_type to
avoid the warning generated with -Wswitch when CDP_NUM_TYPES lacks a case.
Add a new CDP_LAST enum entry used in CDP_NUM_TYPES definition to simplify
adding a new enum entry. Do this to create a cleaner pattern for tracking
the number of enum entries in resctrl in preparation for other enums
needing to do so.
Suggested-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v2:
- Add Ben's RB tag.
Changes since v4:
- Add Tony's Reviewed-by tag.
---
include/linux/resctrl.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 73ff522448a0..c3ae0e8cb522 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -69,9 +69,10 @@ enum resctrl_conf_type {
CDP_NONE,
CDP_CODE,
CDP_DATA,
+ CDP_LAST = CDP_DATA
};
-#define CDP_NUM_TYPES (CDP_DATA + 1)
+#define CDP_NUM_TYPES (CDP_LAST + 1)
/*
* struct pseudo_lock_region - pseudo-lock region information
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 04/10] fs/resctrl: Use accurate type for rdt_resource::rid
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (2 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 03/10] fs/resctrl: Change pattern used to track number of entries in enum Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 05/10] fs/resctrl: Pass error reading event through to user space Reinette Chatre
` (7 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
Every resctrl resource has a unique ID described by enum resctrl_res_level.
enum resctrl_res_level is used in all resource ID initializations and all
resource ID comparisons. All functions consuming the resource ID expects an
enum resctrl_res_level. Of the four structures that contain a resource ID
(struct mon_data, struct mon_evt, struct rdt_domain_hdr, and struct
rdt_resource) only struct rdt_resource does not use enum resctrl_res_level.
Switch the type of rdt_resource::rid to be enum resctrl_res_level to make
it obvious what values are valid, match the type everywhere this member is
used, and obtain benefits from tools that can flag any enum misuse.
Move define of RDT_NUM_RESOURCES outside the enum to enable tools to catch
when a switch() on the resource ID does not handle all the resources and
thus help flag which switch statements need an update when a new resource
is added.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v1:
- Use RDT_RESOURCE_LAST = RDT_RESOURCE_PERF_PKG as last entry in enum.(Ben)
Changes since v2:
- Add Ben's RB tag.
Changes since v4:
- Add Tony's Reviewed-by tag.
---
include/linux/resctrl.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index c3ae0e8cb522..dd09c2ce9a0f 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -54,11 +54,11 @@ enum resctrl_res_level {
RDT_RESOURCE_MBA,
RDT_RESOURCE_SMBA,
RDT_RESOURCE_PERF_PKG,
-
- /* Must be the last */
- RDT_NUM_RESOURCES,
+ RDT_RESOURCE_LAST = RDT_RESOURCE_PERF_PKG
};
+#define RDT_NUM_RESOURCES (RDT_RESOURCE_LAST + 1)
+
/**
* enum resctrl_conf_type - The type of configuration.
* @CDP_NONE: No prioritisation, both code and data are controlled or monitored.
@@ -324,7 +324,7 @@ struct resctrl_mon {
* @cdp_capable: Is the CDP feature available on this resource
*/
struct rdt_resource {
- int rid;
+ enum resctrl_res_level rid;
bool alloc_capable;
bool mon_capable;
enum resctrl_scope ctrl_scope;
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 05/10] fs/resctrl: Pass error reading event through to user space
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (3 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 04/10] fs/resctrl: Use accurate type for rdt_resource::rid Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 06/10] fs/resctrl: Use accurate and symmetric exit flows Reinette Chatre
` (6 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
Reading of event data is managed through populating a struct rmid_read with
properties of event needing to be read. This data is dispatched to an
appropriate CPU and upon completion any error can be found in rmid_read::err,
or on success the event data will be in rmid_read::val.
rmid_read::err is not updated in the unlikely scenario that the reading
of the event was dispatched to a wrong CPU. If this ever occurs due to
a bug in resctrl the user space read will return "success" but the data
reported will be invalid.
Ensure accurate error reporting so that if there may be an issue with
how resctrl picks a CPU it could be learned with an error to user space
instead of silent failure.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v1:
- Add Ben's RB tag.
Changes since V4:
- Add Tony's Reviewed-by tag.
---
fs/resctrl/monitor.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 29b13a690cf3..7f3fe055f7c9 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -458,8 +458,10 @@ static int __l3_mon_event_count(struct rdtgroup *rdtgrp, struct rmid_read *rr)
}
/* Reading a single domain, must be on a CPU in that domain. */
- if (!cpumask_test_cpu(cpu, &d->hdr.cpu_mask))
+ if (!cpumask_test_cpu(cpu, &d->hdr.cpu_mask)) {
+ rr->err = -EIO;
return -EINVAL;
+ }
if (rr->is_mbm_cntr)
rr->err = resctrl_arch_cntr_read(rr->r, d, closid, rmid, cntr_id,
rr->evt->evtid, &tval);
@@ -496,8 +498,10 @@ static int __l3_mon_event_count_sum(struct rdtgroup *rdtgrp, struct rmid_read *r
}
/* Summing domains that share a cache, must be on a CPU for that cache. */
- if (!cpumask_test_cpu(cpu, &rr->ci->shared_cpu_map))
+ if (!cpumask_test_cpu(cpu, &rr->ci->shared_cpu_map)) {
+ rr->err = -EIO;
return -EINVAL;
+ }
/*
* Legacy files must report the sum of an event across all
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 06/10] fs/resctrl: Use accurate and symmetric exit flows
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (4 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 05/10] fs/resctrl: Pass error reading event through to user space Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 07/10] fs/resctrl: Change last_cmd_status custom during input parsing Reinette Chatre
` (5 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
During schemata file write handling there is one error exit path labeled
"out" that handles all cleanup and unlocking needed on exit. The staged
configs cleared during an error exit may not have been used at the time
of exit making the clearing of the staged configs unnecessary.
Access the exit code using two labels and only clear the staged
configuration if it was in use at the time of exit. Doing so makes the
code flow obvious and simplifies upcoming changes that improve the
handling of failures during early input parsing.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v4:
- Add Tony's Reviewed-by tag.
---
fs/resctrl/ctrlmondata.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 2b29fb5a8702..e6ad8927cf50 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -331,7 +331,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
ret = -EINVAL;
rdt_last_cmd_puts("Resource group is pseudo-locked\n");
- goto out;
+ goto out_unlock;
}
rdt_staged_configs_clear();
@@ -341,16 +341,16 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
if (!tok) {
rdt_last_cmd_puts("Missing ':'\n");
ret = -EINVAL;
- goto out;
+ goto out_clear_staged;
}
if (tok[0] == '\0') {
rdt_last_cmd_printf("Missing '%s' value\n", resname);
ret = -EINVAL;
- goto out;
+ goto out_clear_staged;
}
ret = rdtgroup_parse_resource(resname, tok, rdtgrp);
if (ret)
- goto out;
+ goto out_clear_staged;
}
list_for_each_entry(s, &resctrl_schema_all, list) {
@@ -365,7 +365,7 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
ret = resctrl_arch_update_domains(r, rdtgrp->closid);
if (ret)
- goto out;
+ goto out_clear_staged;
}
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
@@ -378,8 +378,9 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
ret = rdtgroup_pseudo_lock_create(rdtgrp);
}
-out:
+out_clear_staged:
rdt_staged_configs_clear();
+out_unlock:
rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 07/10] fs/resctrl: Change last_cmd_status custom during input parsing
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (5 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 06/10] fs/resctrl: Use accurate and symmetric exit flows Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 08/10] fs/resctrl: Add last_cmd_status support for writes to max_threshold_occupancy Reinette Chatre
` (4 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
A pattern of usage of last_cmd_status was introduced during its enabling in
commit
c377dcfbee80 ("x86/intel_rdt: Add diagnostics when writing the schemata file")
and since copied throughout resctrl to result in the following custom:
..._write()
{
/* Early parsing of input, exit on failure. */
/* Obtain rdtgroup_mutex */
rdt_last_cmd_clear(); /* Clear last_cmd_status buffer */
/*
* Act on user command, failures result in detail
* error message in last_cmd_status buffer via
* rdt_last_cmd_puts()/rdt_last_cmd_printf().
*/
/* Release rdtgroup_mutex */
}
If resctrl exits with failure during early parsing of input there are two
possible scenarios:
- The last_cmd_status buffer is empty and a user's read of
info/last_cmd_status returns "ok".
- The last_cmd_status buffer contains details from an earlier ...write()
failure and a user's read of info/last_cmd_status returns this outdated
error description.
Writing to a resctrl file is considered a "resctrl command" and the
resctrl documentation states the following about the last_cmd_status file:
"If the command failed, it will provide more information that can be
conveyed in the error returns from file operations."
Neither of the current scenarios is correct behavior.
Move early input parsing to be done with rdtgroup_mutex held after the
last_cmd_status buffer is cleared. Let info/last_cmd_status be accurate
when an error is encountered during parsing of user command.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v1:
- Add Ben's RB tag.
Changes since v4:
- Rebase on top of the "x86,fs/resctrl: Fix long-standing issues"
series that added locking helpers to info file handlers.
- Add resctrl filename to new error messages to disambiguate the
various "Invalid input" messages. (Tony)
- Add Tony's Reviewed-by tag.
---
fs/resctrl/ctrlmondata.c | 55 ++++++++++++++++----------
fs/resctrl/monitor.c | 60 ++++++++++++++++------------
fs/resctrl/rdtgroup.c | 84 +++++++++++++++++++++++-----------------
3 files changed, 120 insertions(+), 79 deletions(-)
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index e6ad8927cf50..8d5a8b1e659a 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -312,11 +312,6 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
char *tok, *resname;
int ret = 0;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
- buf[nbytes - 1] = '\0';
-
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
rdtgroup_kn_unlock(of->kn);
@@ -324,6 +319,15 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
}
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("schemata: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
/*
* No changes to pseudo-locked region allowed. It has to be removed
* and re-created instead.
@@ -466,11 +470,6 @@ ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
struct rdtgroup *rdtgrp;
int ret = 0;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
- buf[nbytes - 1] = '\0';
-
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
rdtgroup_kn_unlock(of->kn);
@@ -478,6 +477,15 @@ ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
}
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mba_MBps_event: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
if (!strcmp(buf, "mbm_local_bytes")) {
if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
rdtgrp->mba_mbps_event = QOS_L3_MBM_LOCAL_EVENT_ID;
@@ -495,6 +503,7 @@ ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
if (ret)
rdt_last_cmd_printf("Unsupported event id '%s'\n", buf);
+out_unlock:
rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
@@ -858,16 +867,18 @@ ssize_t resctrl_io_alloc_write(struct kernfs_open_file *of, char *buf,
bool enable;
int ret;
- ret = kstrtobool(buf, &enable);
- if (ret)
- return ret;
-
if (!info_kn_lock(of->kn))
return -ENOENT;
r = s->res;
rdt_last_cmd_clear();
+ ret = kstrtobool(buf, &enable);
+ if (ret) {
+ rdt_last_cmd_puts("io_alloc: Invalid input\n");
+ goto out_unlock;
+ }
+
if (!r->cache.io_alloc_capable) {
rdt_last_cmd_printf("io_alloc is not supported on %s\n", s->name);
ret = -ENODEV;
@@ -1022,17 +1033,21 @@ ssize_t resctrl_io_alloc_cbm_write(struct kernfs_open_file *of, char *buf,
u32 io_alloc_closid;
int ret = 0;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
-
- buf[nbytes - 1] = '\0';
-
if (!info_kn_lock(of->kn))
return -ENOENT;
rdt_last_cmd_clear();
r = s->res;
+
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("io_alloc_cbm: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
if (!r->cache.io_alloc_capable) {
rdt_last_cmd_printf("io_alloc is not supported on %s\n", s->name);
ret = -ENODEV;
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index 7f3fe055f7c9..b50da2b02594 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1164,14 +1164,16 @@ ssize_t resctrl_mbm_assign_on_mkdir_write(struct kernfs_open_file *of, char *buf
bool value;
int ret;
- ret = kstrtobool(buf, &value);
- if (ret)
- return ret;
-
if (!info_kn_lock(of->kn))
return -ENOENT;
rdt_last_cmd_clear();
+ ret = kstrtobool(buf, &value);
+ if (ret) {
+ rdt_last_cmd_puts("mbm_assign_on_mkdir: Invalid input\n");
+ goto out_unlock;
+ }
+
if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
ret = -EINVAL;
@@ -1465,17 +1467,20 @@ ssize_t event_filter_write(struct kernfs_open_file *of, char *buf, size_t nbytes
u32 evt_cfg = 0;
int ret = 0;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
-
- buf[nbytes - 1] = '\0';
-
if (!info_kn_lock(of->kn))
return -ENOENT;
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("event_filter: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
r = resctrl_arch_get_resource(mevt->rid);
if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
@@ -1539,17 +1544,20 @@ ssize_t resctrl_mbm_assign_mode_write(struct kernfs_open_file *of, char *buf,
int ret = 0;
bool enable;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
-
- buf[nbytes - 1] = '\0';
-
if (!info_kn_lock(of->kn))
return -ENOENT;
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mbm_assign_mode: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
if (!strcmp(buf, "default")) {
enable = 0;
} else if (!strcmp(buf, "mbm_event")) {
@@ -1823,12 +1831,6 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
char *token, *event;
int ret = 0;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
-
- buf[nbytes - 1] = '\0';
-
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
rdtgroup_kn_unlock(of->kn);
@@ -1836,10 +1838,19 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
}
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mbm_L3_assignments: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ buf[nbytes - 1] = '\0';
+
if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
rdt_last_cmd_puts("mbm_event mode is not enabled\n");
- rdtgroup_kn_unlock(of->kn);
- return -EINVAL;
+ ret = -EINVAL;
+ goto out_unlock;
}
while ((token = strsep(&buf, "\n")) != NULL) {
@@ -1855,6 +1866,7 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
break;
}
+out_unlock:
rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index b5fb59d0e035..a5fe76b0e9eb 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -511,38 +511,40 @@ static int cpus_ctrl_write(struct rdtgroup *rdtgrp, cpumask_var_t newmask,
static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
char *buf, size_t nbytes, loff_t off)
{
- cpumask_var_t tmpmask, newmask, tmpmask1;
+ cpumask_var_t tmpmask = CPUMASK_VAR_NULL, newmask = CPUMASK_VAR_NULL;
+ cpumask_var_t tmpmask1 = CPUMASK_VAR_NULL;
struct rdtgroup *rdtgrp;
int ret;
- if (!buf)
- return -EINVAL;
-
- if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL))
- return -ENOMEM;
- if (!zalloc_cpumask_var(&newmask, GFP_KERNEL)) {
- free_cpumask_var(tmpmask);
- return -ENOMEM;
- }
- if (!zalloc_cpumask_var(&tmpmask1, GFP_KERNEL)) {
- free_cpumask_var(tmpmask);
- free_cpumask_var(newmask);
- return -ENOMEM;
- }
-
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
ret = -ENOENT;
- goto unlock;
+ goto out_unlock;
}
rdt_last_cmd_clear();
+ if (!buf) {
+ rdt_last_cmd_printf("%s: Invalid input\n",
+ is_cpu_list(of) ? "cpus_list" : "cpus");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ if (!zalloc_cpumask_var(&tmpmask, GFP_KERNEL) ||
+ !zalloc_cpumask_var(&newmask, GFP_KERNEL) ||
+ !zalloc_cpumask_var(&tmpmask1, GFP_KERNEL)) {
+ rdt_last_cmd_printf("%s: Kernel allocation failure\n",
+ is_cpu_list(of) ? "cpus_list" : "cpus");
+ ret = -ENOMEM;
+ goto out_free;
+ }
+
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
ret = -EINVAL;
rdt_last_cmd_puts("Pseudo-locking in progress\n");
- goto unlock;
+ goto out_free;
}
if (is_cpu_list(of))
@@ -552,7 +554,7 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
if (ret) {
rdt_last_cmd_puts("Bad CPU list/mask\n");
- goto unlock;
+ goto out_free;
}
/* check that user didn't specify any offline cpus */
@@ -560,7 +562,7 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
if (!cpumask_empty(tmpmask)) {
ret = -EINVAL;
rdt_last_cmd_puts("Can only assign online CPUs\n");
- goto unlock;
+ goto out_free;
}
if (rdtgrp->type == RDTCTRL_GROUP)
@@ -570,11 +572,12 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
else
ret = -EINVAL;
-unlock:
- rdtgroup_kn_unlock(of->kn);
+out_free:
free_cpumask_var(tmpmask);
free_cpumask_var(newmask);
free_cpumask_var(tmpmask1);
+out_unlock:
+ rdtgroup_kn_unlock(of->kn);
return ret ?: nbytes;
}
@@ -1515,11 +1518,6 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
enum rdtgrp_mode mode;
int ret = 0;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
- buf[nbytes - 1] = '\0';
-
rdtgrp = rdtgroup_kn_lock_live(of->kn);
if (!rdtgrp) {
rdtgroup_kn_unlock(of->kn);
@@ -1527,6 +1525,14 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
}
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mode: Invalid input\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ buf[nbytes - 1] = '\0';
mode = rdtgrp->mode;
@@ -1858,19 +1864,23 @@ static ssize_t mbm_total_bytes_config_write(struct kernfs_open_file *of,
struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
int ret;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
-
if (!info_kn_lock(of->kn))
return -ENOENT;
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mbm_total_bytes_config: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
buf[nbytes - 1] = '\0';
ret = mon_config_write(r, buf, QOS_L3_MBM_TOTAL_EVENT_ID);
+out_unlock:
info_kn_unlock(of->kn);
return ret ?: nbytes;
@@ -1883,19 +1893,23 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
int ret;
- /* Valid input requires a trailing newline */
- if (nbytes == 0 || buf[nbytes - 1] != '\n')
- return -EINVAL;
-
if (!info_kn_lock(of->kn))
return -ENOENT;
rdt_last_cmd_clear();
+ /* Valid input requires a trailing newline */
+ if (nbytes == 0 || buf[nbytes - 1] != '\n') {
+ rdt_last_cmd_puts("mbm_local_bytes_config: Invalid input\n");
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
buf[nbytes - 1] = '\0';
ret = mon_config_write(r, buf, QOS_L3_MBM_LOCAL_EVENT_ID);
+out_unlock:
info_kn_unlock(of->kn);
return ret ?: nbytes;
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 08/10] fs/resctrl: Add last_cmd_status support for writes to max_threshold_occupancy
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (6 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 07/10] fs/resctrl: Change last_cmd_status custom during input parsing Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 09/10] fs/resctrl: Communicate resource group deleted error via last_cmd_status Reinette Chatre
` (3 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
info/last_cmd_status is intended to contain more information if a write to
any resctrl file fails. Writes to max_threshold_occupancy did not receive
last_cmd_status support during initial last_cmd_status enabling. Add it now.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v1:
- Add Ben's RB tag.
Changes since v2:
- Switch to guard(). (Chenyu)
- Drop Ben's RB tag due to significant code change.
Changes since v4:
- Rebased on top of the "x86,fs/resctrl: Fix long-standing issues" series
that added locking helpers to info file handlers.
- Add Tony's Reviewed-by tag.
---
fs/resctrl/rdtgroup.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index a5fe76b0e9eb..0e428d337641 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -1300,14 +1300,20 @@ static ssize_t max_threshold_occ_write(struct kernfs_open_file *of,
unsigned int bytes;
int ret;
- ret = kstrtouint(buf, 0, &bytes);
- if (ret)
- return ret;
-
if (!info_kn_lock(of->kn))
return -ENOENT;
+ rdt_last_cmd_clear();
+
+ ret = kstrtouint(buf, 0, &bytes);
+ if (ret) {
+ rdt_last_cmd_puts("max_threshold_occupancy: Invalid input\n");
+ goto out_unlock;
+ }
+
if (bytes > resctrl_rmid_realloc_limit) {
+ rdt_last_cmd_printf("max_threshold_occupancy: Exceeds limit (before adjustment) of %u bytes\n",
+ resctrl_rmid_realloc_limit);
ret = -EINVAL;
goto out_unlock;
}
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 09/10] fs/resctrl: Communicate resource group deleted error via last_cmd_status
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (7 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 08/10] fs/resctrl: Add last_cmd_status support for writes to max_threshold_occupancy Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-01 4:27 ` [PATCH v5 10/10] fs/resctrl: Inform user space when status buffer overflowed Reinette Chatre
` (2 subsequent siblings)
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
User space expects last_cmd_status to contain additional information if
any resctrl command fails.
A resctrl command may be blocked waiting on the rdtgroup_mutex waiting for
another command to finish and find that once the mutex is available that
the resource group has since been deleted. In this scenario the command
will fail while last_cmd_status contains either "ok" if the last_cmd_status
buffer is empty or an outdated error from a previous command failure if
last_cmd_status buffer has content.
Include clearing of last_cmd_status buffer as part of
rdtgroup_kn_lock_live() that is used to obtain access and needed locking
to a resource group before attempting a command on the group. With the
last_cmd_status buffer ready, provide an appropriate message to user space
if the resource group has been deleted.
No last_cmd_status treatment is needed for the remaining failure of
rdtgroup_kn_lock_live() encountering a non-existent resource group since
that could only occur during an attempt to obtain a resource group lock
on a file in info/ which is an invalid usage.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v1:
- Add snippet about why it is safe to dereference the kn to get
to resource group name when resource group is deleted.
Changes since v4:
- Add Tony's Reviewed-by tag.
---
fs/resctrl/ctrlmondata.c | 3 ---
fs/resctrl/monitor.c | 2 --
fs/resctrl/rdtgroup.c | 20 +++++++++++---------
3 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/fs/resctrl/ctrlmondata.c b/fs/resctrl/ctrlmondata.c
index 8d5a8b1e659a..18ec9f564b5a 100644
--- a/fs/resctrl/ctrlmondata.c
+++ b/fs/resctrl/ctrlmondata.c
@@ -317,7 +317,6 @@ ssize_t rdtgroup_schemata_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
- rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
@@ -434,7 +433,6 @@ int rdtgroup_schemata_show(struct kernfs_open_file *of,
}
} else if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
if (!rdtgrp->plr->d) {
- rdt_last_cmd_clear();
rdt_last_cmd_puts("Cache domain offline\n");
ret = -ENODEV;
} else {
@@ -475,7 +473,6 @@ ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
- rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
index b50da2b02594..73413cb128ea 100644
--- a/fs/resctrl/monitor.c
+++ b/fs/resctrl/monitor.c
@@ -1696,7 +1696,6 @@ int mbm_L3_assignments_show(struct kernfs_open_file *of, struct seq_file *s, voi
goto out_unlock;
}
- rdt_last_cmd_clear();
if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
ret = -EINVAL;
@@ -1836,7 +1835,6 @@ ssize_t mbm_L3_assignments_write(struct kernfs_open_file *of, char *buf,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
- rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index 0e428d337641..fa456c469386 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -359,7 +359,6 @@ static int rdtgroup_cpus_show(struct kernfs_open_file *of,
if (rdtgrp) {
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
if (!rdtgrp->plr->d) {
- rdt_last_cmd_clear();
rdt_last_cmd_puts("Cache domain offline\n");
ret = -ENODEV;
} else {
@@ -522,8 +521,6 @@ static ssize_t rdtgroup_cpus_write(struct kernfs_open_file *of,
goto out_unlock;
}
- rdt_last_cmd_clear();
-
if (!buf) {
rdt_last_cmd_printf("%s: Invalid input\n",
is_cpu_list(of) ? "cpus_list" : "cpus");
@@ -788,7 +785,6 @@ static ssize_t rdtgroup_tasks_write(struct kernfs_open_file *of,
rdtgroup_kn_unlock(of->kn);
return -ENOENT;
}
- rdt_last_cmd_clear();
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED ||
rdtgrp->mode == RDT_MODE_PSEUDO_LOCKSETUP) {
@@ -1530,7 +1526,6 @@ static ssize_t rdtgroup_mode_write(struct kernfs_open_file *of,
return -ENOENT;
}
- rdt_last_cmd_clear();
/* Valid input requires a trailing newline */
if (nbytes == 0 || buf[nbytes - 1] != '\n') {
rdt_last_cmd_puts("mode: Invalid input\n");
@@ -1667,7 +1662,6 @@ static int rdtgroup_size_show(struct kernfs_open_file *of,
if (rdtgrp->mode == RDT_MODE_PSEUDO_LOCKED) {
if (!rdtgrp->plr->d) {
- rdt_last_cmd_clear();
rdt_last_cmd_puts("Cache domain offline\n");
ret = -ENODEV;
} else {
@@ -2728,10 +2722,20 @@ struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn)
cpus_read_lock();
mutex_lock(&rdtgroup_mutex);
+ rdt_last_cmd_clear();
/* Was this group deleted while we waited? */
- if (rdtgrp->flags & RDT_DELETED)
+ if (rdtgrp->flags & RDT_DELETED) {
+ /*
+ * It is safe to dereference kn to obtain the resource group's
+ * name because one extra reference to kn is obtained
+ * during resource group creation that will be released by
+ * rdtgroup_remove() called by rdtgroup_kn_put().
+ */
+ rdt_last_cmd_printf("Resource group %s deleted. No commands possible.\n",
+ rdt_kn_name(rdtgrp->kn));
return NULL;
+ }
return rdtgrp;
}
@@ -3945,8 +3949,6 @@ static int mkdir_rdt_prepare(struct kernfs_node *parent_kn,
goto out_unlock;
}
- rdt_last_cmd_clear();
-
/*
* Check that the parent directory for a monitor group is a "mon_groups"
* directory.
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* [PATCH v5 10/10] fs/resctrl: Inform user space when status buffer overflowed
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (8 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 09/10] fs/resctrl: Communicate resource group deleted error via last_cmd_status Reinette Chatre
@ 2026-07-01 4:27 ` Reinette Chatre
2026-07-14 17:49 ` [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
2026-07-14 22:45 ` Moger, Babu
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-01 4:27 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches, reinette.chatre
resctrl fs commands are becoming more powerful with, for example, a user
able to use syntax like '*' to make broad configuration changes. Such
commands that span multiple domains may result in more than one message
printed to the last_cmd_status buffer with more planned.
Display "[truncated]" to user space when displaying the last_cmd_status
buffer to communicate if it overflowed. Upon encountering this user space
is expected to combine details about the failure found in info/last_cmd_status
with related resctrl files to learn the accurate system state after the
command failure.
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
---
Changes since v2:
- Add Ben's RB tag.
Changes since V4:
- Rebased on "x86,fs/resctrl: Fix long-standing issues" series.
- Add Tony's Reviewed-by tag.
---
fs/resctrl/rdtgroup.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
index fa456c469386..efadadfe4ed5 100644
--- a/fs/resctrl/rdtgroup.c
+++ b/fs/resctrl/rdtgroup.c
@@ -979,10 +979,13 @@ static int rdt_last_cmd_status_show(struct kernfs_open_file *of,
if (!info_kn_lock(of->kn))
return -ENOENT;
len = seq_buf_used(&last_cmd_status);
- if (len)
+ if (len) {
seq_printf(seq, "%.*s", len, last_cmd_status_buf);
- else
+ if (seq_buf_has_overflowed(&last_cmd_status))
+ seq_puts(seq, "[truncated]\n");
+ } else {
seq_puts(seq, "ok\n");
+ }
info_kn_unlock(of->kn);
return 0;
}
--
2.54.0
^ permalink raw reply related [flat|nested] 14+ messages in thread* Re: [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (9 preceding siblings ...)
2026-07-01 4:27 ` [PATCH v5 10/10] fs/resctrl: Inform user space when status buffer overflowed Reinette Chatre
@ 2026-07-14 17:49 ` Reinette Chatre
2026-07-14 22:45 ` Moger, Babu
11 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-14 17:49 UTC (permalink / raw)
To: tony.luck, james.morse, Dave.Martin, babu.moger, bp, tglx,
dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches
Dear x86 maintainers,
Could you please consider this series for inclusion? It applies cleanly on top
of x86/cache with HEAD at
2566b5cd6a27 ("fs/resctrl: Fix UAF from worker threads when domains are removed")
There is another resctrl series ("x86,fs/resctrl,arm_mpam: Factor MBA parse-time conversion
to be per-arch") also ready for your consideration. There are no conflicts between it and
this series, they can be considered in any order.
Thank you very much.
Reinette
[1] https://lore.kernel.org/lkml/20260709093111.367851-1-ben.horgan@arm.com/
On 6/30/26 9:27 PM, Reinette Chatre wrote:
> Applies on top of v7.2-rc1 + v5 of "x86,fs/resctrl: Fix long-standing issues":
> https://lore.kernel.org/lkml/cover.1781029125.git.reinette.chatre@intel.com/
>
> Changes since v4:
> - v4: https://lore.kernel.org/lkml/cover.1777419024.git.reinette.chatre@intel.com/
> - Rebased on top of V5 "x86,fs/resctrl: Fix long-standing issues":
> https://lore.kernel.org/lkml/cover.1781029125.git.reinette.chatre@intel.com/
> A significant change in that series is the addition of
> info_kn_lock()/info_kn_unlock() helpers to the info file handlers. With
> the addition of locking to the max_threshold_occ_write() in that series
> it seemed appropriate to re-order the last_cmd_status handling in
> max_threshold_occ_write() to be after the change to last_cmd_status
> custom to contain max_threshold_occ_write() changes to one patch.
> - Add resctrl filename to new error messages to disambiguate the various
> "Invalid input" messages. (Tony)
> - Add Tony's Reviewed-by tag to all patches.
>
> Changes since v3:
> - v3: https://lore.kernel.org/lkml/cover.1775576382.git.reinette.chatre@intel.com/
> - Rebased on v7.1-rc1.
> - Drop "MAINTAINERS: Update resctrl entry" and "fs/resctrl: Add missing return
> value descriptions" that can be found in v7.1-rc1.
> - Drop "fs/resctrl: Avoid "may be used uninitialized" warning" that just does unnecessary
> work to appease compiler warning that is disabled by default. (Boris)
> - Use pr_warn() instead of WARN_ON() in "x86/resctrl: Protect against bad
> shift".
>
> Changes since v2:
> - v2: https://lore.kernel.org/lkml/cover.1774043709.git.reinette.chatre@intel.com/
> - Rebased on top of tip/master with pending resctrl selftest changes,
> https://lore.kernel.org/lkml/cover.1775266384.git.reinette.chatre@intel.com/,
> applied on top to support testing with latest kernel that has pending resctrl
> changes merged.
> - Drop "fs/resctrl: Use stricter checks on input to cpus/cpus_list file"
> that ended up being too strict and removed one use case. (Chris)
> - max_threshold_occ_write() switch to guard(). (Chenyu)
> - Add more detail to one return value description.
> - Add tags.
> - No opinions so far on needing to update last_cmd_status on success of all read
> commands. At this time last_cmd_status will continue to return previous
> failure message (if any) after a read command accessing static data succeeds.
>
> Changes since v1:
> - v1: https://lore.kernel.org/lkml/cover.1772476561.git.reinette.chatre@intel.com/
> - To simplify tracking, include patch to MAINTAINERS submitted separately:
> https://lore.kernel.org/lkml/4274c478922c01f9ceebc805acf991f10a95519f.1771442788.git.reinette.chatre@intel.com/
> - Follow recent upstream changes to add reference to tip tree handbook in
> MAINTAINERS entry.
> - Use new pattern in resctrl to enable looping over all entries of an enum
> while making adding new enum entries more clear all while avoiding warnings
> when compiling with -Wswitch. (Ben)
> - Add another last_cmd_status enhancement that appends "[truncated]" to
> output of info/last_cmd_status if the backing buffer overflowed.
> - Please see patch changelogs for details of changes.
> - Add tags.
>
> Hi Everybody,
>
> This is a collection of resctrl cleanups assembled together for convenience
> and simpler tracking. I'd be happy to split them up if it makes review and/or
> handling easier.
>
> Summary of changes:
>
> - Let resctrl pass stricter checks from various tools to provide a cleaner
> baseline with the goal to promote healthier contributions:
> - ./tools/docs/kernel-doc -Wall -v <files>
> - Build with W=12
> - ./scripts/coccicheck
> - Static checkers
>
> - Use accurate and consistent type for all uses of resource ID.
>
> - In the unlikely scenario that resctrl picked a wrong CPU to read an event
> from, pass the error through to user space instead of claiming to succeed
> and returning a (wrong) result.
>
> - Since inception of last_cmd_status feature there have been mismatches
> between resctrl file operation failures and the contents of
> info/last_cmd_status. This pattern keeps propagating with each new resctrl
> feature. Establish a new baseline with a new pattern that ensures
> info/last_cmd_status contains an accurate failure description that matches
> the most recent resctrl file operation failure.
>
> One potential open:
>
> There remains an inconsistency between resctrl file operations that do/can
> _not_ fail and the contents of info/last_cmd_status. If a resctrl
> file operation fails and an informational error is printed to last_cmd_status
> then a subsequent reading of a resctrl file (specifically most of the files
> found in info/) may succeed while info/last_cmd_status may or may not return
> the error from previous failure.
>
> Ensuring last_cmd_status is reset on every read carries the cost of taking
> rdtgroup_mutex on several more user space initiated paths and thus increase
> contention on rdtgroup_mutex. I opted to not make this change and instead
> focus this work on ensuring that last_cmd_status is accurate whenever there is
> a failure during any resctrl file operation. Please let me know if you have
> opinions in this regard.
>
> Update v5: The addition of the info_kn_lock()/info_kn_unlock() helpers to
> info file handlers now means that rdtgroup_mutex is held every time an info
> file is opened. There is thus now less burden to reset last_cmd_status
> buffer on each info file access. Even so, since there has not been any
> opinions in this regard I opted to keep current behavior.
>
> Any feedback is appreciated.
>
> Regards,
>
> Reinette
>
> Reinette Chatre (10):
> fs/resctrl: Use correct format specifier for printing error pointers
> x86/resctrl: Protect against bad shift
> fs/resctrl: Change pattern used to track number of entries in enum
> fs/resctrl: Use accurate type for rdt_resource::rid
> fs/resctrl: Pass error reading event through to user space
> fs/resctrl: Use accurate and symmetric exit flows
> fs/resctrl: Change last_cmd_status custom during input parsing
> fs/resctrl: Add last_cmd_status support for writes to
> max_threshold_occupancy
> fs/resctrl: Communicate resource group deleted error via
> last_cmd_status
> fs/resctrl: Inform user space when status buffer overflowed
>
> arch/x86/kernel/cpu/resctrl/core.c | 6 +-
> fs/resctrl/ctrlmondata.c | 71 ++++++++++-------
> fs/resctrl/monitor.c | 78 ++++++++++--------
> fs/resctrl/rdtgroup.c | 123 +++++++++++++++++------------
> include/linux/resctrl.h | 11 +--
> 5 files changed, 173 insertions(+), 116 deletions(-)
>
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency
2026-07-01 4:27 [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
` (10 preceding siblings ...)
2026-07-14 17:49 ` [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency Reinette Chatre
@ 2026-07-14 22:45 ` Moger, Babu
2026-07-15 0:00 ` Reinette Chatre
11 siblings, 1 reply; 14+ messages in thread
From: Moger, Babu @ 2026-07-14 22:45 UTC (permalink / raw)
To: Reinette Chatre, tony.luck, james.morse, Dave.Martin, babu.moger,
bp, tglx, dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches
Ran few tests on the series. Looks good.
Tested-by: Babu Moger <babu.moger@amd.com>
On 6/30/2026 11:27 PM, Reinette Chatre wrote:
> Applies on top of v7.2-rc1 + v5 of "x86,fs/resctrl: Fix long-standing issues":
> https://lore.kernel.org/lkml/cover.1781029125.git.reinette.chatre@intel.com/
>
> Changes since v4:
> - v4: https://lore.kernel.org/lkml/cover.1777419024.git.reinette.chatre@intel.com/
> - Rebased on top of V5 "x86,fs/resctrl: Fix long-standing issues":
> https://lore.kernel.org/lkml/cover.1781029125.git.reinette.chatre@intel.com/
> A significant change in that series is the addition of
> info_kn_lock()/info_kn_unlock() helpers to the info file handlers. With
> the addition of locking to the max_threshold_occ_write() in that series
> it seemed appropriate to re-order the last_cmd_status handling in
> max_threshold_occ_write() to be after the change to last_cmd_status
> custom to contain max_threshold_occ_write() changes to one patch.
> - Add resctrl filename to new error messages to disambiguate the various
> "Invalid input" messages. (Tony)
> - Add Tony's Reviewed-by tag to all patches.
>
> Changes since v3:
> - v3: https://lore.kernel.org/lkml/cover.1775576382.git.reinette.chatre@intel.com/
> - Rebased on v7.1-rc1.
> - Drop "MAINTAINERS: Update resctrl entry" and "fs/resctrl: Add missing return
> value descriptions" that can be found in v7.1-rc1.
> - Drop "fs/resctrl: Avoid "may be used uninitialized" warning" that just does unnecessary
> work to appease compiler warning that is disabled by default. (Boris)
> - Use pr_warn() instead of WARN_ON() in "x86/resctrl: Protect against bad
> shift".
>
> Changes since v2:
> - v2: https://lore.kernel.org/lkml/cover.1774043709.git.reinette.chatre@intel.com/
> - Rebased on top of tip/master with pending resctrl selftest changes,
> https://lore.kernel.org/lkml/cover.1775266384.git.reinette.chatre@intel.com/,
> applied on top to support testing with latest kernel that has pending resctrl
> changes merged.
> - Drop "fs/resctrl: Use stricter checks on input to cpus/cpus_list file"
> that ended up being too strict and removed one use case. (Chris)
> - max_threshold_occ_write() switch to guard(). (Chenyu)
> - Add more detail to one return value description.
> - Add tags.
> - No opinions so far on needing to update last_cmd_status on success of all read
> commands. At this time last_cmd_status will continue to return previous
> failure message (if any) after a read command accessing static data succeeds.
>
> Changes since v1:
> - v1: https://lore.kernel.org/lkml/cover.1772476561.git.reinette.chatre@intel.com/
> - To simplify tracking, include patch to MAINTAINERS submitted separately:
> https://lore.kernel.org/lkml/4274c478922c01f9ceebc805acf991f10a95519f.1771442788.git.reinette.chatre@intel.com/
> - Follow recent upstream changes to add reference to tip tree handbook in
> MAINTAINERS entry.
> - Use new pattern in resctrl to enable looping over all entries of an enum
> while making adding new enum entries more clear all while avoiding warnings
> when compiling with -Wswitch. (Ben)
> - Add another last_cmd_status enhancement that appends "[truncated]" to
> output of info/last_cmd_status if the backing buffer overflowed.
> - Please see patch changelogs for details of changes.
> - Add tags.
>
> Hi Everybody,
>
> This is a collection of resctrl cleanups assembled together for convenience
> and simpler tracking. I'd be happy to split them up if it makes review and/or
> handling easier.
>
> Summary of changes:
>
> - Let resctrl pass stricter checks from various tools to provide a cleaner
> baseline with the goal to promote healthier contributions:
> - ./tools/docs/kernel-doc -Wall -v <files>
> - Build with W=12
> - ./scripts/coccicheck
> - Static checkers
>
> - Use accurate and consistent type for all uses of resource ID.
>
> - In the unlikely scenario that resctrl picked a wrong CPU to read an event
> from, pass the error through to user space instead of claiming to succeed
> and returning a (wrong) result.
>
> - Since inception of last_cmd_status feature there have been mismatches
> between resctrl file operation failures and the contents of
> info/last_cmd_status. This pattern keeps propagating with each new resctrl
> feature. Establish a new baseline with a new pattern that ensures
> info/last_cmd_status contains an accurate failure description that matches
> the most recent resctrl file operation failure.
>
> One potential open:
>
> There remains an inconsistency between resctrl file operations that do/can
> _not_ fail and the contents of info/last_cmd_status. If a resctrl
> file operation fails and an informational error is printed to last_cmd_status
> then a subsequent reading of a resctrl file (specifically most of the files
> found in info/) may succeed while info/last_cmd_status may or may not return
> the error from previous failure.
>
> Ensuring last_cmd_status is reset on every read carries the cost of taking
> rdtgroup_mutex on several more user space initiated paths and thus increase
> contention on rdtgroup_mutex. I opted to not make this change and instead
> focus this work on ensuring that last_cmd_status is accurate whenever there is
> a failure during any resctrl file operation. Please let me know if you have
> opinions in this regard.
>
> Update v5: The addition of the info_kn_lock()/info_kn_unlock() helpers to
> info file handlers now means that rdtgroup_mutex is held every time an info
> file is opened. There is thus now less burden to reset last_cmd_status
> buffer on each info file access. Even so, since there has not been any
> opinions in this regard I opted to keep current behavior.
>
> Any feedback is appreciated.
>
> Regards,
>
> Reinette
>
> Reinette Chatre (10):
> fs/resctrl: Use correct format specifier for printing error pointers
> x86/resctrl: Protect against bad shift
> fs/resctrl: Change pattern used to track number of entries in enum
> fs/resctrl: Use accurate type for rdt_resource::rid
> fs/resctrl: Pass error reading event through to user space
> fs/resctrl: Use accurate and symmetric exit flows
> fs/resctrl: Change last_cmd_status custom during input parsing
> fs/resctrl: Add last_cmd_status support for writes to
> max_threshold_occupancy
> fs/resctrl: Communicate resource group deleted error via
> last_cmd_status
> fs/resctrl: Inform user space when status buffer overflowed
>
> arch/x86/kernel/cpu/resctrl/core.c | 6 +-
> fs/resctrl/ctrlmondata.c | 71 ++++++++++-------
> fs/resctrl/monitor.c | 78 ++++++++++--------
> fs/resctrl/rdtgroup.c | 123 +++++++++++++++++------------
> include/linux/resctrl.h | 11 +--
> 5 files changed, 173 insertions(+), 116 deletions(-)
>
^ permalink raw reply [flat|nested] 14+ messages in thread* Re: [PATCH v5 00/10] x86,fs/resctrl: Improve resctrl quality and consistency
2026-07-14 22:45 ` Moger, Babu
@ 2026-07-15 0:00 ` Reinette Chatre
0 siblings, 0 replies; 14+ messages in thread
From: Reinette Chatre @ 2026-07-15 0:00 UTC (permalink / raw)
To: Moger, Babu, tony.luck, james.morse, Dave.Martin, babu.moger, bp,
tglx, dave.hansen
Cc: x86, hpa, ben.horgan, fustini, fenghuay, peternewman, yu.c.chen,
linux-kernel, patches
On 7/14/26 3:45 PM, Moger, Babu wrote:
> Ran few tests on the series. Looks good.
>
> Tested-by: Babu Moger <babu.moger@amd.com>
Thank you very much Babu.
Reinette
^ permalink raw reply [flat|nested] 14+ messages in thread