On 1/20/2025 11:16 AM, Zi Yan wrote:
On Sun Jan 19, 2025 at 7:37 PM EST, Hyeonggon Yoo wrote:On 1/18/2025 4:09 AM, Zi Yan wrote:On 17 Jan 2025, at 0:00, Hyeonggon Yoo wrote:On 1/6/2025 9:06 PM, Bruno Faccini wrote:Current fake-numa implementation prevents new Numa nodes to be later hot-plugged by drivers. A common symptom of this limitation is the "node <X> was absent from the node_possible_map" message by associated warning in mm/memory_hotplug.c: add_memory_resource(). This comes from the lack of remapping in both pxm_to_node_map[] and node_to_pxm_map[] tables to take fake-numa nodes into account and thus triggers collisions with original and physical nodes only-mapping that had been determined from BIOS tables. This patch fixes this by doing the necessary node-ids translation in both pxm_to_node_map[]/node_to_pxm_map[] tables. node_distance[] table has also been fixed accordingly. Signed-off-by: Bruno Faccini <bfaccini@xxxxxxxxxx>Hi Bruno, This commit causes WARN() and disables fakenuma when I pass "numa=fake=4U" on my QEMU setup. Attaching WARN() log and git bisect log to help debugging.Is your VM getting 4 NUMA nodes at the end?No, it only gets node 0 at the end.Got it.Can you also share your QEMU command line and your kernel config?The config is attached (fakenuma.config) QEMU command line: $ qemu-system-x86_64 \ -cpu host \ -enable-kvm \ -smp $(nproc) \ -m 32G \ -nographic \ -kernel arch/x86/boot/bzImage \ -initrd ../../rootfs.cpio.gz \ -nic user,model=virtio-net-pci \ -append "console=ttyS0 numa=fake=4U"This can help Bruno reproduce the issue locally. At least, I cannot reproduce it on mm-everything-2025-01-16-23-18.Still reproduced on mm-everything-2025-01-18-04-55 with my setup.I also notice that my VM does not have “No NUMA configuration found” (in your log) in its kernel log and that might explain why I could not reproduce it.Did you do NUMA configuration (-numa in QEMU) for your VM? I didn't, but it's still expected to work 'cause it's fake numa.No. It seems that the "No NUMA configuration found" is caused by your qemu, where dummy_numa_init() is used (maybe ACPI SRAT is not populated?)
FYI, Yes. ACPI SRAT is not populated. $ qemu-system-x86_64 --version QEMU emulator version 6.2.0 (Debian 1:6.2+dfsg-2ubuntu6.24) Copyright (c) 2003-2021 Fabrice Bellard and the QEMU Project developers
I used the patch below to emulate the situation and reproduced the issue. Since dummy_numa_init() is used when there is no underlying NUMA architecture, NUMA initialization fails, or NUMA is disabled on the command line (the last does not apply here), it should be properly handled. I will let Bruno look into it. Thank you for the info. diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index 64e5cdb2460a..70dfd9bfb23f 100644 --- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c @@ -223,7 +223,7 @@ static int __init dummy_numa_init(void) */ void __init x86_numa_init(void) { - if (!numa_off) { + if (0 && !numa_off) { #ifdef CONFIG_ACPI_NUMA if (!numa_init(x86_acpi_numa_init)) return;[WARN() splat] [ 0.009676] No NUMA configuration found [ 0.009677] Faking a node at [mem 0x0000000000000000-0x000000083fffffff] [ 0.009705] Fake node size 16895MB too small, increasing to 16896MB [ 0.009708] Faking node 0 at [mem 0x0000000000001000-0x0000000420000fff] (16896MB) [ 0.009711] Faking node 1 at [mem 0x0000000420001000-0x000000083fffffff] (16895MB) [ 0.009738] ------------[ cut here ]------------ [ 0.009739] -1 max nid when expected 1 [ 0.009760] WARNING: CPU: 0 PID: 0 at drivers/acpi/numa/srat.c:120 fix_pxm_node_maps+0x577/0x810 [ 0.009766] Modules linked in: [ 0.009769] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.13.0-rc6+ #31 [ 0.009771] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 0.009772] RIP: 0010:fix_pxm_node_maps+0x577/0x810 [ 0.009774] Code: 8b 85 40 ff ff ff 44 8b 8d 44 ff ff ff 8b 85 48 ff ff ff e9 83 fb ff ff 44 89 f2 44 89 ce 48 c7 c7 aa 2f 84 8d e8 b9 71 01 fe <0f> 0b 41 b8 ff ff ff ff e9 ba fb ff ff 48 c7 c7 a0 d8 d1 8d 44 89 [ 0.009776] RSP: 0000:ffffffff8da03be0 EFLAGS: 00010046 ORIG_RAX: 0000000000000000 [ 0.009778] RAX: 0000000000000000 RBX: 0000000000000400 RCX: 0000000000000000 [ 0.009779] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 0.009780] RBP: ffffffff8da03ca8 R08: 0000000000000000 R09: 0000000000000000 [ 0.009781] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 [ 0.009782] R13: 00000000000007ff R14: 0000000000000001 R15: 0000000000000000 [ 0.009783] FS: 0000000000000000(0000) GS:ffffffff8de8c000(0000) knlGS:0000000000000000 [ 0.009784] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.009785] CR2: ffff90e4bde01000 CR3: 00000001bd03e000 CR4: 00000000000200b0 [ 0.009788] Call Trace: [ 0.009790] <TASK> [ 0.009792] ? show_regs+0x71/0x90 [ 0.009797] ? __warn+0x8d/0x150 [ 0.009799] ? fix_pxm_node_maps+0x577/0x810 [ 0.009802] ? report_bug+0x1ab/0x1c0 [ 0.009805] ? fixup_exception+0x27/0x380 [ 0.009809] ? early_fixup_exception+0xa2/0xf0 [ 0.009813] ? do_early_exception+0x28/0x90 [ 0.009816] ? early_idt_handler_common+0x2f/0x3a [ 0.009819] ? fix_pxm_node_maps+0x577/0x810 [ 0.009822] ? numa_cleanup_meminfo+0x8c/0x5b0 [ 0.009828] numa_emulation+0x4e3/0xad0 [ 0.009830] ? __pfx_dummy_numa_init+0x10/0x10 [ 0.009833] ? __pfx_dummy_numa_init+0x10/0x10 [ 0.009836] numa_memblks_init+0x10c/0x2c0 [ 0.009838] ? __pfx_dummy_numa_init+0x10/0x10 [ 0.009840] numa_init+0x61/0x3e0 [ 0.009842] ? topology_register_boot_apic+0x2a/0x40 [ 0.009846] x86_numa_init+0x65/0x80 [ 0.009848] initmem_init+0xe/0x20 [ 0.009850] setup_arch+0x9d8/0xfa0 [ 0.009852] ? _printk+0x58/0x90 [ 0.009855] start_kernel+0x5f/0xb50 [ 0.009860] x86_64_start_reservations+0x18/0x30 [ 0.009863] x86_64_start_kernel+0xc0/0x110 [ 0.009864] ? setup_ghcb+0xe/0x140 [ 0.009867] common_startup_64+0x13e/0x141 [ 0.009871] </TASK> [ 0.009871] ---[ end trace 0000000000000000 ]--- [Git bisect log] # bad: [f378252a2168c2fbf8fc08b635061e5f6748c1f2] kasan: sw_tags: use str_on_off() helper in kasan_init_sw_tags() git bisect bad f378252a2168c2fbf8fc08b635061e5f6748c1f2 # good: [cbc5dde0a461240046e8a41c43d7c3b76d5db952] fs/proc: fix softlockup in __read_vmcore (part 2) git bisect good cbc5dde0a461240046e8a41c43d7c3b76d5db952 # good: [fb73203263021f2ee9dd54d280b1c543d10acd76] mm: move common part of pagetable_*_ctor to helper git bisect good fb73203263021f2ee9dd54d280b1c543d10acd76 # bad: [8fd966c9310f14d5bbe653cf087853582170aad6] mm, swap: remove old allocation path for HDD git bisect bad 8fd966c9310f14d5bbe653cf087853582170aad6 # bad: [8646971f02651146554233d63fdd721f5f060973] mm: shmem: skip swapcache for swapin of synchronous swap device git bisect bad 8646971f02651146554233d63fdd721f5f060973 # good: [b8ba614eaa8dd31702c61e7df7231b1b18b99259] mm/damon/paddr: report filter-passed bytes back for DAMOS_STAT action git bisect good b8ba614eaa8dd31702c61e7df7231b1b18b99259 # good: [fd0935b8e9e8c2edf05a3d0ffa09d0aa3e9cf2dd] Docs/ABI/damon: document per-region DAMOS filter-passed bytes stat file git bisect good fd0935b8e9e8c2edf05a3d0ffa09d0aa3e9cf2dd # good: [3ffd3cd7e2e8793d3b5fbb83c03668c47ab6d599] selftests/damon: remove tests for DAMON debugfs interface git bisect good 3ffd3cd7e2e8793d3b5fbb83c03668c47ab6d599 # good: [bf9f93f0b7bff8af780330f5094775a39caf3612] mm/damon: remove DAMON debugfs interface git bisect good bf9f93f0b7bff8af780330f5094775a39caf3612 # bad: [1746744be6ff271e29345a5be4cc144aa33b10ab] mm/memmap: prevent double scanning of memmap by kmemleak git bisect bad 1746744be6ff271e29345a5be4cc144aa33b10ab # bad: [ca19a5ab8756ef78c34d02d2b8c266a9cc7bf57d] mm/fake-numa: allow later numa node hotplug git bisect bad ca19a5ab8756ef78c34d02d2b8c266a9cc7bf57d # first bad commit: [ca19a5ab8756ef78c34d02d2b8c266a9cc7bf57d] mm/fake-numa: allow later numa node hotplug--- drivers/acpi/numa/srat.c | 86 ++++++++++++++++++++++++++++++++++++ include/acpi/acpi_numa.h | 5 +++ include/linux/numa_memblks.h | 3 ++ mm/numa_emulation.c | 45 ++++++++++++++++--- mm/numa_memblks.c | 2 +- 5 files changed, 133 insertions(+), 8 deletions(-) diff --git a/drivers/acpi/numa/srat.c b/drivers/acpi/numa/srat.c index bec0dcd1f9c3..59fffe34c9d0 100644 --- a/drivers/acpi/numa/srat.c +++ b/drivers/acpi/numa/srat.c @@ -81,6 +81,92 @@ int acpi_map_pxm_to_node(int pxm) } EXPORT_SYMBOL(acpi_map_pxm_to_node); +#ifdef CONFIG_NUMA_EMU +/* + * Take max_nid - 1 fake-numa nodes into account in both + * pxm_to_node_map()/node_to_pxm_map[] tables. + */ +int __init fix_pxm_node_maps(int max_nid) +{ + static int pxm_to_node_map_copy[MAX_PXM_DOMAINS] __initdata + = { [0 ... MAX_PXM_DOMAINS - 1] = NUMA_NO_NODE }; + static int node_to_pxm_map_copy[MAX_NUMNODES] __initdata + = { [0 ... MAX_NUMNODES - 1] = PXM_INVAL }; + int i, j, index = -1, count = 0; + nodemask_t nodes_to_enable; + + if (numa_off || srat_disabled()) + return -1; + + /* find fake nodes PXM mapping */ + for (i = 0; i < MAX_NUMNODES; i++) { + if (node_to_pxm_map[i] != PXM_INVAL) { + for (j = 0; j <= max_nid; j++) { + if ((emu_nid_to_phys[j] == i) && + WARN(node_to_pxm_map_copy[j] != PXM_INVAL, + "Node %d is already binded to PXM %d\n", + j, node_to_pxm_map_copy[j])) + return -1; + if (emu_nid_to_phys[j] == i) { + node_to_pxm_map_copy[j] = + node_to_pxm_map[i]; + if (j > index) + index = j; + count++; + } + } + } + } + if (WARN(index != max_nid, "%d max nid when expected %d\n", + index, max_nid)) + return -1; + + nodes_clear(nodes_to_enable); + + /* map phys nodes not used for fake nodes */ + for (i = 0; i < MAX_NUMNODES; i++) { + if (node_to_pxm_map[i] != PXM_INVAL) { + for (j = 0; j <= max_nid; j++) + if (emu_nid_to_phys[j] == i) + break; + /* fake nodes PXM mapping has been done */ + if (j <= max_nid) + continue; + /* find first hole */ + for (j = 0; + j < MAX_NUMNODES && + node_to_pxm_map_copy[j] != PXM_INVAL; + j++) + ; + if (WARN(j == MAX_NUMNODES, + "Number of nodes exceeds MAX_NUMNODES\n")) + return -1; + node_to_pxm_map_copy[j] = node_to_pxm_map[i]; + node_set(j, nodes_to_enable); + count++; + } + } + + /* creating reverse mapping in pxm_to_node_map[] */ + for (i = 0; i < MAX_NUMNODES; i++) + if (node_to_pxm_map_copy[i] != PXM_INVAL && + pxm_to_node_map_copy[node_to_pxm_map_copy[i]] == NUMA_NO_NODE) + pxm_to_node_map_copy[node_to_pxm_map_copy[i]] = i; + + /* overwrite with new mapping */ + for (i = 0; i < MAX_NUMNODES; i++) { + node_to_pxm_map[i] = node_to_pxm_map_copy[i]; + pxm_to_node_map[i] = pxm_to_node_map_copy[i]; + } + + /* enable other nodes found in PXM for hotplug */ + nodes_or(numa_nodes_parsed, nodes_to_enable, numa_nodes_parsed); + + pr_debug("found %d total number of nodes\n", count); + return 0; +} +#endif + static void __init acpi_table_print_srat_entry(struct acpi_subtable_header *header) { diff --git a/include/acpi/acpi_numa.h b/include/acpi/acpi_numa.h index b5f594754a9e..99b960bd473c 100644 --- a/include/acpi/acpi_numa.h +++ b/include/acpi/acpi_numa.h @@ -17,11 +17,16 @@ extern int node_to_pxm(int); extern int acpi_map_pxm_to_node(int); extern unsigned char acpi_srat_revision; extern void disable_srat(void); +extern int fix_pxm_node_maps(int max_nid); extern void bad_srat(void); extern int srat_disabled(void); #else /* CONFIG_ACPI_NUMA */ +static inline int fix_pxm_node_maps(int max_nid) +{ + return 0; +} static inline void disable_srat(void) { } diff --git a/include/linux/numa_memblks.h b/include/linux/numa_memblks.h index cfad6ce7e1bd..dd85613cdd86 100644 --- a/include/linux/numa_memblks.h +++ b/include/linux/numa_memblks.h @@ -29,7 +29,10 @@ int __init numa_cleanup_meminfo(struct numa_meminfo *mi); int __init numa_memblks_init(int (*init_func)(void), bool memblock_force_top_down); +extern int numa_distance_cnt; + #ifdef CONFIG_NUMA_EMU +extern int emu_nid_to_phys[MAX_NUMNODES]; int numa_emu_cmdline(char *str); void __init numa_emu_update_cpu_to_node(int *emu_nid_to_phys, unsigned int nr_emu_nids); diff --git a/mm/numa_emulation.c b/mm/numa_emulation.c index 031fb9961bf7..9d55679d99ce 100644 --- a/mm/numa_emulation.c +++ b/mm/numa_emulation.c @@ -8,11 +8,12 @@ #include <linux/memblock.h> #include <linux/numa_memblks.h> #include <asm/numa.h> +#include <acpi/acpi_numa.h> #define FAKE_NODE_MIN_SIZE ((u64)32 << 20) #define FAKE_NODE_MIN_HASH_MASK (~(FAKE_NODE_MIN_SIZE - 1UL)) -static int emu_nid_to_phys[MAX_NUMNODES]; +int emu_nid_to_phys[MAX_NUMNODES]; static char *emu_cmdline __initdata; int __init numa_emu_cmdline(char *str) @@ -379,6 +380,7 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) size_t phys_size = numa_dist_cnt * numa_dist_cnt * sizeof(phys_dist[0]); int max_emu_nid, dfl_phys_nid; int i, j, ret; + nodemask_t physnode_mask = numa_nodes_parsed; if (!emu_cmdline) goto no_emu; @@ -395,7 +397,6 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) * split the system RAM into N fake nodes. */ if (strchr(emu_cmdline, 'U')) { - nodemask_t physnode_mask = numa_nodes_parsed; unsigned long n; int nid = 0; @@ -465,9 +466,6 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) */ max_emu_nid = setup_emu2phys_nid(&dfl_phys_nid); - /* commit */ - *numa_meminfo = ei; - /* Make sure numa_nodes_parsed only contains emulated nodes */ nodes_clear(numa_nodes_parsed); for (i = 0; i < ARRAY_SIZE(ei.blk); i++) @@ -475,10 +473,21 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) ei.blk[i].nid != NUMA_NO_NODE) node_set(ei.blk[i].nid, numa_nodes_parsed); - numa_emu_update_cpu_to_node(emu_nid_to_phys, ARRAY_SIZE(emu_nid_to_phys)); + /* fix pxm_to_node_map[] and node_to_pxm_map[] to avoid collision + * with faked numa nodes, particularly during later memory hotplug + * handling, and also update numa_nodes_parsed accordingly. + */ + ret = fix_pxm_node_maps(max_emu_nid); + if (ret < 0) + goto no_emu; + + /* commit */ + *numa_meminfo = ei; + + numa_emu_update_cpu_to_node(emu_nid_to_phys, max_emu_nid + 1); /* make sure all emulated nodes are mapped to a physical node */ - for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) + for (i = 0; i < max_emu_nid + 1; i++) if (emu_nid_to_phys[i] == NUMA_NO_NODE) emu_nid_to_phys[i] = dfl_phys_nid; @@ -501,12 +510,34 @@ void __init numa_emulation(struct numa_meminfo *numa_meminfo, int numa_dist_cnt) numa_set_distance(i, j, dist); } } + for (i = 0; i < numa_distance_cnt; i++) { + for (j = 0; j < numa_distance_cnt; j++) { + int physi, physj; + u8 dist; + + /* distance between fake nodes is already ok */ + if (emu_nid_to_phys[i] != NUMA_NO_NODE && + emu_nid_to_phys[j] != NUMA_NO_NODE) + continue; + if (emu_nid_to_phys[i] != NUMA_NO_NODE) + physi = emu_nid_to_phys[i]; + else + physi = i - max_emu_nid; + if (emu_nid_to_phys[j] != NUMA_NO_NODE) + physj = emu_nid_to_phys[j]; + else + physj = j - max_emu_nid; + dist = phys_dist[physi * numa_dist_cnt + physj]; + numa_set_distance(i, j, dist); + } + } /* free the copied physical distance table */ memblock_free(phys_dist, phys_size); return; no_emu: + numa_nodes_parsed = physnode_mask; /* No emulation. Build identity emu_nid_to_phys[] for numa_add_cpu() */ for (i = 0; i < ARRAY_SIZE(emu_nid_to_phys); i++) emu_nid_to_phys[i] = i; diff --git a/mm/numa_memblks.c b/mm/numa_memblks.c index a3877e9bc878..ff4054f4334d 100644 --- a/mm/numa_memblks.c +++ b/mm/numa_memblks.c @@ -7,7 +7,7 @@ #include <linux/numa.h> #include <linux/numa_memblks.h> -static int numa_distance_cnt; +int numa_distance_cnt; static u8 *numa_distance; nodemask_t numa_nodes_parsed __initdata;Best Regards, Yan, Zi
