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charset=UTF-8 Date: Thu, 25 Jun 2026 14:37:00 -0400 Message-Id: Cc: , , , , , To: "Zhen Ni" , , From: "Zi Yan" Subject: Re: [PATCH v11 2/4] mm/page_owner: add NUMA node filter X-Mailer: aerc 0.21.0 References: <20260625043101.338794-1-zhen.ni@easystack.cn> <20260625043101.338794-3-zhen.ni@easystack.cn> In-Reply-To: <20260625043101.338794-3-zhen.ni@easystack.cn> X-ClientProxiedBy: CH5P223CA0003.NAMP223.PROD.OUTLOOK.COM (2603:10b6:610:1f3::19) To IA0PR12MB8374.namprd12.prod.outlook.com (2603:10b6:208:40e::7) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: IA0PR12MB8374:EE_|SA1PR12MB6971:EE_ X-MS-Office365-Filtering-Correlation-Id: 6bd8693e-e411-41a5-272d-08ded2e8bf0e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|23010399003|366016|1800799024|4143699003|22082099003|11063799006|18002099003|5023799004|56012099006|6133799003|3023799007; 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This is useful for NUMA-aware memory > allocation analysis and debugging. > > The filter supports flexible input formats: > - Single node: nid=3D0 > - Multiple nodes: nid=3D0,2,3 > - Node range: nid=3D0-3 > - Mixed format: nid=3D0,2-4,7 > > Example usage: > # Using the page_owner_filter tool (recommended) > ./page_owner_filter -n 0-3 > ./page_owner_filter -m stack_handle -n 0,2-4,7 > > The implementation uses per-file-descriptor filter state stored in > file->private_data, allowing each opener to have independent filter > configuration. It uses nodemask_t for efficient multi-node filtering and > nodelist_parse() for flexible input parsing. Node validity is verified > using nodes_subset() to reject nodes without memory. > > Signed-off-by: Zhen Ni > --- > Changes in v11: > - Remove 'nid' member from struct page_owner to save memory > - Read page->flags directly with poison checking > > Changes in v10: > - Add 'nid' member to struct page_owner and record it at allocation time > - Remove cond_resched() in page iteration loop (unconditional call) > - Update NUMA filter to use saved nid instead of page_to_nid() > > Changes in v9: > - Add spinlock protection for NUMA filter state access > - Use memdesc_nid() instead of page_to_nid() to bypass PF_POISONED_CHECK(= ) > > Changes in v8: > - Add cond_resched() in page iteration loop to prevent RCU stalls > - Reject empty nid list to avoid enabling an empty filter > - Improve comment: "Commit all filter changes" > > Changes in v7: > - per-file-descriptor implementation > > Changes in v6: > - Add node validity check using nodes_subset > to reject invalid node numbers that don't exist in the system > - Move bool filter_by_nid declaration to top of block > - Use kmalloc_objs instead of kmalloc > - Remove 100 bytes overhead > > Changes in v5: > - Optimize nodes_empty() check in page iteration loop > - Add __data_racy qualifier to nid_mask field > > Changes in v4: > - Remove "-1" support, use empty string to clear filter > - Use strncpy_from_user() instead of copy_from_user() > - Add concurrency safety documentation for nid_mask access > - Rename fops to page_owner_nid_filter_fops for consistency > > Changes in v3: > - Remove READ_ONCE/WRITE_ONCE for nodemask_t (fixes compilation errors) > * nodemask_t is a large structure (128 bytes) that triggers compile-tim= e asserts > * Direct assignment is safe for this use case > - Add comment explaining input length calculation formula > * 6 bytes =3D ",NNNNN" (comma + 5-digit node number) > - Simplify "-1" check using kstrtoint() instead of dual strcmp() > - Move nodemask_t mask read outside PFN iteration loop for performance > * Avoids 128-byte structure copy on each iteration > > Changes in v2: > - Use nodemask_t instead of int to support multiple nodes > - Implement nodelist_parse() to support flexible input formats > * Single node: "0", "2" > * Multiple nodes: "0,2,3" > * Ranges: "0-3" > * Mixed: "0,2-4,7" > - Use %*pbl format for output (e.g., "0-2", "0,2-4,7") > - Use dynamic memory allocation (kmalloc) to handle variable-length input > - Follow cpuset's max_write_len pattern: (100 + 6 * MAX_NUMNODES) > > v10: https://lore.kernel.org/linux-mm/20260618035750.3724613-3-zhen.ni@ea= systack.cn/ > v9: https://lore.kernel.org/linux-mm/20260525081652.2210206-3-zhen.ni@eas= ystack.cn/ > v8: https://lore.kernel.org/linux-mm/20260520075641.1931080-3-zhen.ni@eas= ystack.cn/ > v7: https://lore.kernel.org/linux-mm/20260515091942.1535677-3-zhen.ni@eas= ystack.cn/ > v6: https://lore.kernel.org/linux-mm/20260511033017.747781-3-zhen.ni@easy= stack.cn/ > v5: https://lore.kernel.org/linux-mm/20260507064643.179187-3-zhen.ni@easy= stack.cn/ > v4: https://lore.kernel.org/linux-mm/20260430163247.13628-3-zhen.ni@easys= tack.cn/ > v3: https://lore.kernel.org/linux-mm/20260428071112.1420380-4-zhen.ni@eas= ystack.cn/ > v2: https://lore.kernel.org/linux-mm/20260419155540.376847-4-zhen.ni@easy= stack.cn/ > v1: https://lore.kernel.org/linux-mm/20260417154638.22370-4-zhen.ni@easys= tack.cn/ > --- > mm/page_owner.c | 61 +++++++++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 59 insertions(+), 2 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 7595735979bf..cae5abf0ac9a 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -68,6 +68,8 @@ static const char * const page_owner_print_mode_strings= [] =3D { > =20 > struct page_owner_filter_state { > enum page_owner_print_mode print_mode; > + nodemask_t nid_filter; > + bool nid_filter_enabled; I thought about initializing nid_filter to node_states[N_MEMORY] to get rid of nid_filter_enabled, but that adds unncessary nid filtering to all page_ower reads. Your approach is better. > spinlock_t lock; > }; > =20 > @@ -698,6 +700,7 @@ read_page_owner(struct file *file, char __user *buf, = size_t count, loff_t *ppos) > struct page_owner *page_owner; > depot_stack_handle_t handle; > struct page_owner_filter_state *state =3D file->private_data; > + unsigned long flags; > =20 > if (!static_branch_unlikely(&page_owner_inited)) > return -EINVAL; > @@ -774,6 +777,27 @@ read_page_owner(struct file *file, char __user *buf,= size_t count, loff_t *ppos) > if (!handle) > goto ext_put_continue; > =20 > + spin_lock_irqsave(&state->lock, flags); > + if (state->nid_filter_enabled) { > + int nid; > + memdesc_flags_t page_flags =3D READ_ONCE(page->flags); > + > + /* > + * Bypass PF_POISONED_CHECK() in page_to_nid() to avoid > + * VM_BUG_ON when accessing poisoned pages. > + */ > + if (page_flags.f =3D=3D PAGE_POISON_PATTERN) { > + spin_unlock_irqrestore(&state->lock, flags); > + goto ext_put_continue; > + } > + nid =3D memdesc_nid(page_flags); > + if (!node_isset(nid, state->nid_filter)) { > + spin_unlock_irqrestore(&state->lock, flags); > + goto ext_put_continue; > + } > + } > + spin_unlock_irqrestore(&state->lock, flags); > + > /* Record the next PFN to read in the file offset */ > *ppos =3D pfn + 1; > =20 > @@ -783,6 +807,7 @@ read_page_owner(struct file *file, char __user *buf, = size_t count, loff_t *ppos) > &page_owner_tmp, handle, state); > ext_put_continue: > page_ext_put(page_ext); > + cond_resched(); In the changelog above, cond_resched() is said to be removed in V10. Did you miss this? Or it is intended. Otherwise, LGTM. Acked-by: Zi Yan --=20 Best Regards, Yan, Zi