When perf-record with a large AUX area, e.g 4GB, it fails with:
#perf record -C 0 -m ,4G -e arm_spe_0// -- sleep 1
failed to mmap with 12 (Cannot allocate memory)
and it reveals a WARNING with __alloc_pages():
[ 66.595604] ------------[ cut here ]------------
[ 66.600206] WARNING: CPU: 44 PID: 17573 at mm/page_alloc.c:5568 __alloc_pages+0x1ec/0x248
[ 66.608375] Modules linked in: ip6table_filter(E) ip6_tables(E) iptable_filter(E) ebtable_nat(E) ebtables(E) aes_ce_blk(E) vfat(E) fat(E) aes_ce_cipher(E) crct10dif_ce(E) ghash_ce(E) sm4_ce_cipher(E) sm4(E) sha2_ce(E) sha256_arm64(E) sha1_ce(E) acpi_ipmi(E) sbsa_gwdt(E) sg(E) ipmi_si(E) ipmi_devintf(E) ipmi_msghandler(E) ip_tables(E) sd_mod(E) ast(E) drm_kms_helper(E) syscopyarea(E) sysfillrect(E) nvme(E) sysimgblt(E) i2c_algo_bit(E) nvme_core(E) drm_shmem_helper(E) ahci(E) t10_pi(E) libahci(E) drm(E) crc64_rocksoft(E) i40e(E) crc64(E) libata(E) i2c_core(E)
[ 66.657719] CPU: 44 PID: 17573 Comm: perf Kdump: loaded Tainted: G E 6.3.0-rc4+ #58
[ 66.666749] Hardware name: Default Default/Default, BIOS 1.2.M1.AL.P.139.00 03/22/2023
[ 66.674650] pstate: 23400009 (nzCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
[ 66.681597] pc : __alloc_pages+0x1ec/0x248
[ 66.685680] lr : __kmalloc_large_node+0xc0/0x1f8
[ 66.690285] sp : ffff800020523980
[ 66.693585] pmr_save: 000000e0
[ 66.696624] x29: ffff800020523980 x28: ffff000832975800 x27: 0000000000000000
[ 66.703746] x26: 0000000000100000 x25: 0000000000100000 x24: ffff8000083615d0
[ 66.710866] x23: 0000000000040dc0 x22: ffff000823d6d140 x21: 000000000000000b
[ 66.717987] x20: 000000000000000b x19: 0000000000000000 x18: 0000000000000030
[ 66.725108] x17: 0000000000000000 x16: ffff800008f05be8 x15: ffff000823d6d6d0
[ 66.732229] x14: 0000000000000000 x13: 343373656761705f x12: 726e202c30206574
[ 66.739350] x11: 00000000ffff7fff x10: 00000000ffff7fff x9 : ffff8000083af570
[ 66.746471] x8 : 00000000000bffe8 x7 : c0000000ffff7fff x6 : 000000000005fff4
[ 66.753592] x5 : 0000000000000000 x4 : ffff000823d6d8d8 x3 : 0000000000000000
[ 66.760713] x2 : 0000000000000000 x1 : 0000000000000001 x0 : 0000000000040dc0
[ 66.767834] Call trace:
[ 66.770267] __alloc_pages+0x1ec/0x248
[ 66.774003] __kmalloc_large_node+0xc0/0x1f8
[ 66.778259] __kmalloc_node+0x134/0x1e8
[ 66.782081] rb_alloc_aux+0xe0/0x298
[ 66.785643] perf_mmap+0x440/0x660
[ 66.789031] mmap_region+0x308/0x8a8
[ 66.792593] do_mmap+0x3c0/0x528
[ 66.795807] vm_mmap_pgoff+0xf4/0x1b8
[ 66.799456] ksys_mmap_pgoff+0x18c/0x218
[ 66.803365] __arm64_sys_mmap+0x38/0x58
[ 66.807187] invoke_syscall+0x50/0x128
[ 66.810922] el0_svc_common.constprop.0+0x58/0x188
[ 66.815698] do_el0_svc+0x34/0x50
[ 66.818999] el0_svc+0x34/0x108
[ 66.822127] el0t_64_sync_handler+0xb8/0xc0
[ 66.826296] el0t_64_sync+0x1a4/0x1a8
[ 66.829946] ---[ end trace 0000000000000000 ]---
'rb->aux_pages' allocated by kcalloc() is a pointer array which is used to
maintains AUX trace pages. The allocated page for this array is physically
contiguous (and virtually contiguous) with an order of 0..MAX_ORDER. If the
size of pointer array crosses the limitation set by MAX_ORDER, it reveals a
WARNING.
So bail out early with -EINVAL if the request AUX area is out of bound,
e.g.:
#perf record -C 0 -m ,4G -e arm_spe_0// -- sleep 1
failed to mmap with 22 (Invalid argument)
Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
---
changes since v1:
- drop out patch2 because it has been fixed on upstream (Thanks James for reminding)
- move sanity check into rb_alloc_aux (per Leo)
- add overflow check (per James)
---
kernel/events/ring_buffer.c | 13 +++++++++++++
tools/perf/Documentation/perf-record.txt | 3 ++-
2 files changed, 15 insertions(+), 1 deletion(-)
diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c
index a0433f37b024..e514aaba9d42 100644
--- a/kernel/events/ring_buffer.c
+++ b/kernel/events/ring_buffer.c
@@ -673,6 +673,7 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
bool overwrite = !(flags & RING_BUFFER_WRITABLE);
int node = (event->cpu == -1) ? -1 : cpu_to_node(event->cpu);
int ret = -ENOMEM, max_order;
+ size_t bytes;
if (!has_aux(event))
return -EOPNOTSUPP;
@@ -699,6 +700,18 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
watermark = 0;
}
+ /*
+ * 'rb->aux_pages' allocated by kcalloc() is a pointer array which is
+ * used to maintains AUX trace pages. The allocated page for this array
+ * is physically contiguous (and virtually contiguous) with an order of
+ * 0..MAX_ORDER. If the size of pointer array crosses the limitation set
+ * by MAX_ORDER, it reveals a WARNING.
+ *
+ * So bail out early if the request AUX area is out of bound.
+ */
+ if (check_mul_overflow(nr_pages, sizeof(void *), &bytes) ||
+ get_order(bytes) > MAX_ORDER)
+ return -EINVAL;
rb->aux_pages = kcalloc_node(nr_pages, sizeof(void *), GFP_KERNEL,
node);
if (!rb->aux_pages)
diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 680396c56bd1..5d8d3ad084ed 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -290,7 +290,8 @@ OPTIONS
specification with appended unit character - B/K/M/G. The
size is rounded up to have nearest pages power of two value.
Also, by adding a comma, the number of mmap pages for AUX
- area tracing can be specified.
+ area tracing can be specified. With MAX_ORDER set as 10 on
+ arm64 platform , the maximum AUX area is limited to 2GiB.
-g::
Enables call-graph (stack chain/backtrace) recording for both
--
2.20.1.12.g72788fdb
