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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Jun 2025 05:59:13.1528 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d8ded103-750c-4ef0-8ba4-08ddb2e43ed3 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SJ5PEPF00000209.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY8PR12MB7337 Content-Type: text/plain; charset="utf-8" A new scalar value (PTEAScanScale) to control per task PTE A bit scanning is introduced. 0 : scanning disabled 1-10 : scanning enabled. In future PTEAScanScale could be used to control aggressiveness of scanning. CC: linux-doc@vger.kernel.org CC: Jonathan Corbet CC: linux-fsdevel@vger.kernel.org Suggested-by: David Rientjes Signed-off-by: Raghavendra K T --- Documentation/filesystems/proc.rst | 2 ++ fs/proc/task_mmu.c | 4 ++++ include/linux/mm_types.h | 3 +++ include/uapi/linux/prctl.h | 7 +++++++ kernel/fork.c | 4 ++++ kernel/sys.c | 25 +++++++++++++++++++++++++ mm/kscand.c | 5 +++++ 7 files changed, 50 insertions(+) Rebasing to upstream tree will change prctl number. diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems= /proc.rst index 2a17865dfe39..429409c341ac 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -205,6 +205,7 @@ read the file /proc/PID/status:: VmLib: 1412 kB VmPTE: 20 kb VmSwap: 0 kB + PTEAScanScale: 0 HugetlbPages: 0 kB CoreDumping: 0 THP_enabled: 1 @@ -288,6 +289,7 @@ It's slow but very precise. VmPTE size of page table entries VmSwap amount of swap used by anonymous private data (shmem swap usage is not included) + PTEAScanScale Integer representing async PTE A bit scan agr= ression HugetlbPages size of hugetlb memory portions CoreDumping process's memory is currently being dumped (killing the process may lead to a corrupted = core) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 994cde10e3f4..6a1a660d9824 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -79,6 +79,10 @@ void task_mem(struct seq_file *m, struct mm_struct *mm) " kB\nVmPTE:\t", mm_pgtables_bytes(mm) >> 10, 8); SEQ_PUT_DEC(" kB\nVmSwap:\t", swap); seq_puts(m, " kB\n"); +#ifdef CONFIG_KSCAND + seq_put_decimal_ull_width(m, "PTEAScanScale:\t", mm->pte_scan_scale, 8); + seq_puts(m, "\n"); +#endif hugetlb_report_usage(m, mm); } #undef SEQ_PUT_DEC diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 571be1ad12ab..ffdb9207cc4f 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1112,6 +1112,9 @@ struct mm_struct { #ifdef CONFIG_KSCAND /* Tracks promotion node. XXX: use nodemask */ int target_node; + + /* Integer representing PTE A bit scan aggression (0-10) */ + unsigned int pte_scan_scale; #endif /* * An operation with batched TLB flushing is going on. Anything diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index 15c18ef4eb11..2f64a80e5cdf 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -364,4 +364,11 @@ struct prctl_mm_map { # define PR_TIMER_CREATE_RESTORE_IDS_ON 1 # define PR_TIMER_CREATE_RESTORE_IDS_GET 2 =20 +/* Set/get PTE A bit scan scale */ +#define PR_SET_PTE_A_SCAN_SCALE 78 +#define PR_GET_PTE_A_SCAN_SCALE 79 +# define PR_PTE_A_SCAN_SCALE_MIN 0 +# define PR_PTE_A_SCAN_SCALE_MAX 10 +# define PR_PTE_A_SCAN_SCALE_DEFAULT 1 + #endif /* _LINUX_PRCTL_H */ diff --git a/kernel/fork.c b/kernel/fork.c index af6dd315b106..120ee2ba7d30 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -106,6 +106,7 @@ #include #include #include +#include =20 #include #include @@ -1311,6 +1312,9 @@ static struct mm_struct *mm_init(struct mm_struct *mm= , struct task_struct *p, init_tlb_flush_pending(mm); #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !defined(CONFIG_SPLIT_PMD_PTLO= CKS) mm->pmd_huge_pte =3D NULL; +#endif +#ifdef CONFIG_KSCAND + mm->pte_scan_scale =3D PR_PTE_A_SCAN_SCALE_DEFAULT; #endif mm_init_uprobes_state(mm); hugetlb_count_init(mm); diff --git a/kernel/sys.c b/kernel/sys.c index c434968e9f5d..aff92ff2c7dd 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2146,6 +2146,19 @@ static int prctl_set_auxv(struct mm_struct *mm, unsi= gned long addr, =20 return 0; } +#ifdef CONFIG_KSCAND +static int prctl_pte_scan_scale_write(unsigned int scale) +{ + scale =3D clamp(scale, PR_PTE_A_SCAN_SCALE_MIN, PR_PTE_A_SCAN_SCALE_MAX); + current->mm->pte_scan_scale =3D scale; + return 0; +} + +static unsigned int prctl_pte_scan_scale_read(void) +{ + return current->mm->pte_scan_scale; +} +#endif =20 static int prctl_set_mm(int opt, unsigned long addr, unsigned long arg4, unsigned long arg5) @@ -2820,6 +2833,18 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, a= rg2, unsigned long, arg3, return -EINVAL; error =3D posixtimer_create_prctl(arg2); break; +#ifdef CONFIG_KSCAND + case PR_SET_PTE_A_SCAN_SCALE: + if (arg3 || arg4 || arg5) + return -EINVAL; + error =3D prctl_pte_scan_scale_write((unsigned int) arg2); + break; + case PR_GET_PTE_A_SCAN_SCALE: + if (arg2 || arg3 || arg4 || arg5) + return -EINVAL; + error =3D prctl_pte_scan_scale_read(); + break; +#endif default: trace_task_prctl_unknown(option, arg2, arg3, arg4, arg5); error =3D -EINVAL; diff --git a/mm/kscand.c b/mm/kscand.c index 029d6d2bedc3..2be7e71c2c8f 100644 --- a/mm/kscand.c +++ b/mm/kscand.c @@ -1228,6 +1228,11 @@ static unsigned long kscand_scan_mm_slot(void) goto outerloop; } =20 + if (!mm->pte_scan_scale) { + next_mm =3D true; + goto outerloop; + } + mm_target_node =3D READ_ONCE(mm->target_node); if (mm_target_node !=3D mm_slot_target_node) WRITE_ONCE(mm->target_node, mm_slot_target_node); --=20 2.34.1