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Howlett" Cc: SeongJae Park , Andrew Morton , maple-tree@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Suren Baghdasaryan , Matthew Wilcox , Sidhartha Kumar , Vlastimil Babka , Alice Ryhl , Kuninori Morimoto , Geert Uytterhoeven , Arnd Bergmann , Christian Kujau Subject: Re: [PATCH v3 21/30] maple_tree: Add cp_is_new_root() helper Date: Tue, 3 Feb 2026 22:36:19 -0800 Message-ID: <20260204063620.15857-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Stat-Signature: kfw517sxmr4wxkffzdg8np1rw46cu56y X-Rspamd-Queue-Id: 533B240002 X-Rspam-User: X-HE-Tag: 1770186990-131717 X-HE-Meta: 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 tQORNYS0 bF7hKWW7jmnSHrgHmtLZpC1WCvIVD+6I1arAz7Pj4iZXpmIVJ+8D07uK/kYOHk61UaDRgRZsDC3vuKR471B71z4vy2cqwCGvjI+FyYjhYAZ0dbOkqL1uxcwaR2Ftz2PpdJqAS61t0Y/OpbPjkdfWY1zfqmI3BkdFKHkbekTpN18ijmpvTpt1RpdfC038rgfryqGKzv7u8i64Bm3WN7g2MZaCiZE9Q2LVeYpx2cXKocupF9iLjn/xo6E8UwdLHDxw1K7IXD4E66PuWSbQbuVEyMbhnVA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 3 Feb 2026 12:26:44 -0500 "Liam R. Howlett" wrote: > > Andrew, > > Please apply this fix to remove warnings on older compilers. I've compiled the > lot against gcc 8.1 and 9.3 with only this fix needed. I also confirmed the below patch passes my build tests. > > Thanks again, SJ, for looking at these patches! You're welcome, that's my pleasure :) > > Regards, > Liam > > ------------------------------------------------------------------------------- > diff --git a/lib/maple_tree.c b/lib/maple_tree.c > index 42038e42a4c7e..22cbaba72931f 100644 > --- a/lib/maple_tree.c > +++ b/lib/maple_tree.c > @@ -3361,7 +3361,7 @@ static inline bool cp_is_new_root(struct maple_copy *cp, struct ma_state *mas) > * read-side operations that can view it until it is insert into > * the tree after an rcu_assign_pointer() call. > */ > - RCU_INIT_POINTER(cp->slot[0], mt_mk_node(cp->dst[0].node, mt)); > + ma_init_slot(cp->slot[0], cp->dst[0].node, mt); > cp->height++; > } > WARN_ON_ONCE(cp->dst[0].node != mte_to_node( But, I found mm-new of today triggers below warning during booting on my test machine. And git-bisect points this fixup patch. I further found reverting this patch makes the booting success without the below warning. I have no idea about the root cause, so reporting first. [ 0.447863] ------------[ cut here ]------------ [ 0.449019] WARNING: lib/maple_tree.c:2617 at mas_wr_split+0x116d/0x1270, CPU#0: swapper/0/0 [ 0.451068] Modules linked in: [ 0.451745] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.19.0-rc6+ #263 PREEMPT(voluntary) [ 0.453653] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 0.455282] RIP: 0010:mas_wr_split (lib/maple_tree.c:2617 (discriminator 1) lib/maple_tree.c:2590 (discriminator 1) lib/maple_tree.c:3400 (discriminator 1) lib/maple_tree.c:3462 (discriminator 1)) [ 0.456071] Code: ff ff ff 40 88 7b 4f 88 53 4d 4c 89 43 08 48 89 4b 10 48 89 6b 20 4c 89 63 28 e9 27 fe ff ff 4c 39 e2 0f 45 f8 e9 e7 f2 ff ff <0f> 0b e9 78 f8 ff ff 48 c7 44 24 10 00 00 00 00 b9 01 00 00 09 All code ======== 0: ff (bad) 1: ff (bad) 2: ff 40 88 incl -0x78(%rax) 5: 7b 4f jnp 0x56 7: 88 53 4d mov %dl,0x4d(%rbx) a: 4c 89 43 08 mov %r8,0x8(%rbx) e: 48 89 4b 10 mov %rcx,0x10(%rbx) 12: 48 89 6b 20 mov %rbp,0x20(%rbx) 16: 4c 89 63 28 mov %r12,0x28(%rbx) 1a: e9 27 fe ff ff jmp 0xfffffffffffffe46 1f: 4c 39 e2 cmp %r12,%rdx 22: 0f 45 f8 cmovne %eax,%edi 25: e9 e7 f2 ff ff jmp 0xfffffffffffff311 2a:* 0f 0b ud2 <-- trapping instruction 2c: e9 78 f8 ff ff jmp 0xfffffffffffff8a9 31: 48 c7 44 24 10 00 00 movq $0x0,0x10(%rsp) 38: 00 00 3a: b9 01 00 00 09 mov $0x9000001,%ecx Code starting with the faulting instruction =========================================== 0: 0f 0b ud2 2: e9 78 f8 ff ff jmp 0xfffffffffffff87f 7: 48 c7 44 24 10 00 00 movq $0x0,0x10(%rsp) e: 00 00 10: b9 01 00 00 09 mov $0x9000001,%ecx [ 0.460144] RSP: 0000:ffffffff9b803ba0 EFLAGS: 00010087 [ 0.461338] RAX: ffff8c6b8022f600 RBX: ffffffff9b803e78 RCX: 0000000000000000 [ 0.462915] RDX: ffff8c6b8022ee00 RSI: 0000000000000001 RDI: ffff8c6b8022ee50 [ 0.464498] RBP: 0000000000000003 R08: 0000000000000001 R09: 0000000000000003 [ 0.466099] R10: 0000000000000002 R11: ffff8c6b8022ee00 R12: ffffffff9b803c90 [ 0.467676] R13: ffffffff9b803e78 R14: 0000000000000001 R15: ffffffff9b803c78 [ 0.469244] FS: 0000000000000000(0000) GS:ffff8c6ccfce7000(0000) knlGS:0000000000000000 [ 0.470862] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 0.471827] CR2: ffff8c6c40801000 CR3: 00000001bf624000 CR4: 00000000000000b0 [ 0.473238] Call Trace: [ 0.473861] [ 0.474326] mas_store_gfp (lib/maple_tree.c:4890) [ 0.475159] early_irq_init (kernel/irq/irqdesc.c:197 (discriminator 2) kernel/irq/irqdesc.c:572 (discriminator 2)) [ 0.476105] start_kernel (init/main.c:1112) [ 0.476922] x86_64_start_reservations (arch/x86/kernel/head64.c:310) [ 0.477950] x86_64_start_kernel (??:?) [ 0.478854] common_startup_64 (arch/x86/kernel/head_64.S:419) [ 0.479761] [ 0.480243] ---[ end trace 0000000000000000 ]--- Thanks, SJ [...]