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linux/include/trace/events
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Kalesh Singh 079c24d569 mm/tracing: rss_stat: ensure curr is false from kthread context 
The rss_stat trace event allows userspace tools, like Perfetto [1], to
inspect per-process RSS metric changes over time.

The curr field was introduced to rss_stat in commit e4dcad204d
("rss_stat: add support to detect RSS updates of external mm").  Its
intent is to indicate whether the RSS update is for the mm_struct of the
current execution context; and is set to false when operating on a remote
mm_struct (e.g., via kswapd or a direct reclaimer).

However, an issue arises when a kernel thread temporarily adopts a user
process's mm_struct.  Kernel threads do not have their own mm_struct and
normally have current->mm set to NULL.  To operate on user memory, they
can "borrow" a memory context using kthread_use_mm(), which sets
current->mm to the user process's mm.

This can be observed, for example, in the USB Function Filesystem (FFS)
driver.  The ffs_user_copy_worker() handles AIO completions and uses
kthread_use_mm() to copy data to a user-space buffer.  If a page fault
occurs during this copy, the fault handler executes in the kthread's
context.

At this point, current is the kthread, but current->mm points to the user
process's mm.  Since the rss_stat event (from the page fault) is for that
same mm, the condition current->mm == mm becomes true, causing curr to be
incorrectly set to true when the trace event is emitted.

This is misleading because it suggests the mm belongs to the kthread,
confusing userspace tools that track per-process RSS changes and
corrupting their mm_id-to-process association.

Fix this by ensuring curr is always false when the trace event is emitted
from a kthread context by checking for the PF_KTHREAD flag.

Link: https://lkml.kernel.org/r/20260219233708.1971199-1-kaleshsingh@google.com
Link: https://perfetto.dev/ [1]
Fixes: e4dcad204d ("rss_stat: add support to detect RSS updates of external mm")
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Cc: "David Hildenbrand (Arm)" <david@kernel.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>	[5.10+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-02-24 11:13:27 -08:00
..
9p.h 9p: prevent read overrun in protocol dump tracepoint 2023-12-05 21:18:44 +09:00
afs.h afs: Add support for RENAME_NOREPLACE and RENAME_EXCHANGE 2025-09-25 09:19:07 +02:00
alarmtimer.h alarmtimer: Hide alarmtimer_suspend event when RTC_CLASS is not configured 2025-07-21 16:40:56 -04:00
amdxdna.h accel/amdxdna: Add command execution 2024-11-22 11:43:27 -07:00
asoc.h ASoC: asoc.h: convert to snd_soc_dapm_xxx() 2025-11-17 00:14:25 +00:00
avc.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
bcache.h
block.h block: fix blk_zone_append_update_request_bio() kernel-doc 2025-07-16 10:02:18 -06:00
bpf_test_run.h bpf: add bpf_modify_return_test_tp() kfunc triggering tracepoint 2024-03-28 18:31:40 -07:00
bridge.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
btrfs.h btrfs: fix NULL dereference on root when tracing inode eviction 2025-12-16 22:53:14 +01:00
cachefiles.h cachefiles: Add auxiliary data trace 2024-12-20 22:34:05 +01:00
capability.h security: add trace event for cap_capable 2024-12-04 20:59:21 -06:00
ceph.h ceph: add trace points to the MDS client 2025-12-10 11:50:54 +01:00
cgroup.h cgroup: increase maximum subsystem count from 16 to 32 2026-02-01 06:34:15 -10:00
clk.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
cma.h mm/cma: add 'available count' and 'total count' to trace_cma_alloc_start 2025-09-13 16:55:15 -07:00
compaction.h mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages 2024-02-22 10:24:50 -08:00
context_tracking.h
cpuhp.h
csd.h smp: Change function signatures to use call_single_data_t 2023-09-13 14:59:24 +02:00
damon.h mm/damon/core: add trace point for damos stat per apply interval 2026-01-20 19:24:46 -08:00
devfreq.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
devlink.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
dlm.h dlm: remove lkb from callback tracepoints 2024-04-01 13:31:12 -05:00
dma_buf.h dma-buf: add some tracepoints to debug. 2026-01-21 13:27:54 +01:00
dma_fence.h dma-fence: Add safe access helpers and document the rules 2025-06-13 08:26:49 +01:00
dma.h tracing/dma: Cap dma_map_sg tracepoint arrays to prevent buffer overflow 2026-02-02 08:41:17 +01:00
erofs.h erofs: pass inode to trace_erofs_read_folio 2026-01-23 20:02:09 +08:00
error_report.h
exceptions.h x86/tracing, x86/mm: Move page fault tracepoints to generic 2025-05-16 10:13:59 +02:00
ext4.h ext4: mark move extents fast-commit ineligible 2026-01-19 19:26:35 -05:00
f2fs.h f2fs: introduce trace_f2fs_priority_update 2026-01-31 03:24:55 +00:00
fib.h ipv4: Convert ->flowi4_tos to dscp_t. 2025-08-26 17:34:31 -07:00
fib6.h tracing: ipv6: Add flow label to fib6_table_lookup tracepoint 2024-12-19 16:02:22 +01:00
filelock.h vfs-6.18-rc1.inode 2025-09-29 09:42:30 -07:00
filemap.h filemap: add trace events for get_pages, map_pages, and fault 2024-09-01 20:26:10 -07:00
firewire_ohci.h firewire: ohci: add tracepoints event for data of Self-ID DMA 2024-07-04 09:07:14 +09:00
firewire.h firewire: core: rename cause flag of tracepoints event 2024-09-12 22:30:38 +09:00
fs_dax.h mm: update core kernel code to use vm_flags_t consistently 2025-07-09 22:42:13 -07:00
fscache.h cachefiles: fix slab-use-after-free in fscache_withdraw_volume() 2024-07-03 10:36:14 +02:00
fsi_master_aspeed.h
fsi_master_ast_cf.h
fsi_master_gpio.h
fsi_master_i2cr.h fsi: Add IBM I2C Responder virtual FSI master 2023-08-11 13:32:14 +09:30
fsi.h fsi: core: Add trace events for scan and unregister 2023-08-09 15:43:28 +09:30
fsverity.h fsverity: add tracepoints 2026-01-29 16:00:57 +01:00
gpio.h
gpu_mem.h
habanalabs.h accel/habanalabs: fix typo in trace output (cms -> cmd) 2025-09-25 09:09:28 +03:00
handshake.h net/handshake: Trace events for TLS Alert helpers 2023-07-28 14:07:59 -07:00
host1x.h
huge_memory.h mm/khugepaged: map dirty/writeback pages failures to EAGAIN 2026-01-26 20:02:12 -08:00
hugetlbfs.h hugetlb: fix NULL pointer dereference in trace_hugetlbfs_alloc_inode 2025-01-12 19:03:36 -08:00
hw_pressure.h sched/cpufreq: Rename arch_update_thermal_pressure() => arch_update_hw_pressure() 2024-04-24 12:08:01 +02:00
hwmon.h hwmon: Introduce 64-bit energy attribute support 2025-09-07 16:33:48 -07:00
i2c_slave.h
i2c.h
ib_mad.h IB/mad: Don't call to function that might sleep while in atomic context 2022-11-10 10:57:15 +02:00
ib_umad.h
icmp.h net/ipv4: add tracepoint for icmp_send 2024-05-08 10:39:26 +01:00
initcall.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
intel_ifs.h trace: platform/x86/intel/ifs: Add SBAF trace support 2024-08-12 16:36:11 +02:00
intel_ish.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
intel-sst.h
io_uring.h io_uring/trace: rename io_uring_queue_async_work event "rw" field 2025-12-04 07:18:02 -07:00
iocost.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
iommu.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
ipi.h tracing: arm: arm64: Hide trace events ipi_raise, ipi_entry and ipi_exit 2025-07-23 14:58:55 -04:00
irq_matrix.h genirq/matrix: Remove unused irq_matrix_alloc_reserved tracepoint 2025-06-02 13:12:26 -04:00
irq.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
iscsi.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
jbd2.h jbd2: remove journal_clean_one_cp_list() 2023-07-10 23:09:21 -04:00
kmem.h mm/tracing: rss_stat: ensure curr is false from kthread context 2026-02-24 11:13:27 -08:00
ksm.h mm/ksm: add tracepoint for ksm advisor 2023-12-29 11:58:27 -08:00
kvm.h LoongArch: KVM: Move kvm_iocsr tracepoint out of generic code 2025-09-23 23:37:26 +08:00
kyber.h kyber: Replace strlcpy with strscpy 2023-07-17 08:18:17 -06:00
libata.h
lock.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
maple_tree.h Maple Tree: add new data structure 2022-09-26 19:46:13 -07:00
mce.h x86/MCE/AMD: Add support for new MCA_SYND{1,2} registers 2024-10-31 10:36:07 +01:00
mctp.h
mdio.h trace: events: cleanup deprecated strncpy uses 2024-04-05 22:10:25 -07:00
memcg.h memcg: add flush tracepoint 2024-11-11 00:26:46 -08:00
memory-failure.h mm/memory-failure: remove the selection of RAS 2025-11-24 15:08:55 -08:00
migrate.h mm/migrate: add MR_DAMON to migrate_reason 2024-07-03 19:30:12 -07:00
mlxsw.h
mmap_lock.h mm: mmap_lock: optimize mmap_lock tracepoints 2025-01-13 22:40:34 -08:00
mmap.h mm: remove unused mmap tracepoints 2025-07-09 22:41:55 -07:00
mmc.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
mmflags.h mm: introduce VM_MAYBE_GUARD and make visible in /proc/$pid/smaps 2025-11-20 13:43:58 -08:00
module.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
mptcp.h trace: mptcp: add mptcp_rcvbuf_grow tracepoint 2026-02-04 18:45:09 -08:00
napi.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
nbd.h nbd: Use NULL to represent a pointer 2024-05-14 07:22:35 -06:00
neigh.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
net_probe_common.h trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters 2024-04-03 19:26:14 -07:00
net.h net: add net cookie for net device trace events 2025-11-04 09:59:19 +01:00
netfs.h netfs: Fix race between cache write completion and ALL_QUEUED being set 2025-07-14 11:05:02 +02:00
netlink.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
nilfs2.h nilfs2: use __field_struct() for a bitwise field 2024-05-11 15:51:43 -07:00
nmi.h
notifier.h notifiers: add tracepoints to the notifiers infrastructure 2023-04-08 13:45:38 -07:00
objagg.h
oom.h mm: improve code consistency with zonelist_* helper functions 2024-09-01 20:25:55 -07:00
osnoise.h trace/osnoise: Add trace events for samples 2025-02-26 19:44:30 -05:00
page_isolation.h
page_pool.h page_pool: devmem support 2024-09-11 20:44:31 -07:00
page_ref.h mm: introduce memdesc_flags_t 2025-09-13 16:55:07 -07:00
pagemap.h
pci.h PCI: trace: Add RAS tracepoint to monitor link speed changes 2025-12-23 16:06:00 -06:00
percpu.h
power_cpu_migrate.h
power.h PM: Introduce new PMSG_POWEROFF event 2025-11-14 17:05:53 +01:00
preemptirq.h tracing: Remove definition of trace_*_rcuidle() 2024-10-08 21:17:39 -04:00
printk.h
pwc.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
pwm.h pwm: Add tracing for waveform callbacks 2024-09-28 15:13:56 +02:00
qdisc.h tracing/net_sched: NULL pointer dereference in perf_trace_qdisc_reset() 2024-06-27 11:06:30 +02:00
qla.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
qrtr.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
rcu.h RCU pull request for v6.15 2025-03-24 19:41:37 -07:00
rdma_core.h
readahead.h readahead: add trace points 2025-09-21 14:22:28 -07:00
regulator.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
rpcgss.h sunrpc: implement rfc2203 rpcsec_gss seqnum cache 2025-05-19 10:14:29 -04:00
rpcrdma.h svcrdma: Handle device removal outside of the CM event handler 2024-09-20 19:31:03 -04:00
rpm.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
rseq.h rseq: Cache CPU ID and MM CID values 2025-11-04 08:32:14 +01:00
rtc.h
rust_sample.h rust: samples: add tracepoint to Rust sample 2024-11-04 16:21:44 -05:00
rwmmio.h asm-generic/io: Add _RET_IP_ to MMIO trace for more accurate debug info 2022-11-21 22:02:10 +01:00
rxrpc.h rxrpc: Fix recvmsg() unconditional requeue 2026-01-19 10:07:06 -08:00
sched_ext.h sched_ext: Implement load balancer for bypass mode 2025-11-12 06:43:44 -10:00
sched.h tracing changes for 6.17 2025-08-01 10:29:36 -07:00
scmi.h include: trace: Add tracepoint support for inflight xfer count 2025-07-03 16:18:09 +01:00
scsi.h scsi: trace: Show rtn in string for scsi_dispatch_cmd_error() 2025-06-09 21:59:07 -04:00
sctp.h
signal.h
siox.h
skb.h net: add rx_sk to trace_kfree_skb 2024-06-19 12:44:22 +01:00
smbus.h
sock.h net: Retire DCCP socket. 2025-04-11 18:58:10 -07:00
sof_intel.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
sof.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
spi-mem.h spi: spi-mem: Trace exec_op 2025-10-27 11:10:50 +00:00
spi.h spi: Fix spelling typos and acronyms capitalization 2023-07-11 14:14:32 +01:00
spmi.h
sunrpc.h sunrpc: remove SVC_SYSERR 2025-07-14 12:46:48 -04:00
sunvnet.h
swiotlb.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
syscalls.h tracing: Declare system call tracepoints with TRACE_EVENT_SYSCALL 2024-10-09 17:05:54 -04:00
target.h scsi: usb: Rename the RESERVE and RELEASE constants 2025-02-12 22:20:55 -05:00
task.h copy_process: pass clone_flags as u64 across calltree 2025-09-01 15:31:34 +02:00
tcp.h tcp: preserve const qualifier in tcp_rsk() and inet_rsk() 2026-01-21 19:20:04 -08:00
tegra_apb_dma.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
thp.h powerpc/thp: tracing: Hide hugepage events under CONFIG_PPC_BOOK3S_64 2025-07-25 08:58:07 -04:00
timer_migration.h timers/migration: Rename 'online' bit to 'available' 2025-11-20 20:17:31 +01:00
timer.h tracing/timers: Rename the hrtimer_init event to hrtimer_setup 2025-04-05 10:30:17 +02:00
timestamp.h fs: tracepoints around multigrain timestamp events 2024-10-10 10:20:52 +02:00
tlb.h x86/mm/tlb/trace: Export the TLB_REMOTE_WRONG_CPU enum in <trace/events/tlb.h> 2025-12-13 11:01:16 +01:00
tsm_mr.h tsm-mr: Add TVM Measurement Register support 2025-05-08 19:17:33 -07:00
udp.h trace: adjust TP_STORE_ADDR_PORTS_SKB() parameters 2024-04-03 19:26:14 -07:00
v4l2.h
vb2.h
vmalloc.h mm: vmalloc: add free_vmap_area_noflush trace event 2022-11-08 17:37:17 -08:00
vmscan.h mm/vmscan: add tracepoint and reason for kswapd_failures reset 2026-01-31 14:22:38 -08:00
vsock_virtio_transport_common.h vsock/virtio: MSG_ZEROCOPY flag support 2023-09-21 12:34:00 +02:00
watchdog.h watchdog: Add tracing events for the most usual watchdog events 2022-10-12 09:47:02 +02:00
wbt.h blk-wbt: Replace strlcpy with strscpy 2023-07-17 08:18:17 -06:00
workqueue.h tracing/treewide: Remove second parameter of __assign_str() 2024-05-22 20:14:47 -04:00
writeback.h mm.git review status for linus..mm-stable 2026-02-12 11:32:37 -08:00
xdp.h xdp: tracing: Hide some xdp events under CONFIG_BPF_SYSCALL 2025-06-12 19:36:53 -07:00
xen.h x86/xen: move paravirt lazy code 2023-09-19 07:04:49 +02:00