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McKenney" Subject: Re: [PATCH v3] mm/mm_init: Don't cond_resched() in deferred_init_memmap_chunk() if called from deferred_grow_zone() Message-ID: References: <20260122184343.546627-1-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260122184343.546627-1-longman@redhat.com> X-Rspamd-Queue-Id: 3D2AB40003 X-Stat-Signature: wu4u9q15ociaohox1nucd9e4dc3u16nc X-Rspam-User: X-Rspamd-Server: rspam02 X-HE-Tag: 1769158086-933633 X-HE-Meta: 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 pA1rjzCh creOOub6QAq+WH6UEcUR0ZcwNuOmMpkEp29dTV1KPX0O2bc1f3/bglREzcVhYipvjQ9keioFMotR707E= 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 Thu, Jan 22, 2026 at 01:43:43PM -0500, Waiman Long wrote: > Commit 3acb913c9d5b ("mm/mm_init: use deferred_init_memmap_chunk() > in deferred_grow_zone()") made deferred_grow_zone() call > deferred_init_memmap_chunk() within a pgdat_resize_lock() critical > section with irqs disabled. It did check for irqs_disabled() in > deferred_init_memmap_chunk() to avoid calling cond_resched(). For a > PREEMPT_RT kernel build, however, spin_lock_irqsave() does not disable > interrupt but rcu_read_lock() is called. This leads to the following > bug report. > > BUG: sleeping function called from invalid context at mm/mm_init.c:2091 > in_atomic(): 0, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0 > preempt_count: 0, expected: 0 > RCU nest depth: 1, expected: 0 > 3 locks held by swapper/0/1: > #0: ffff80008471b7a0 (sched_domains_mutex){+.+.}-{4:4}, at: sched_domains_mutex_lock+0x28/0x40 > #1: ffff003bdfffef48 (&pgdat->node_size_lock){+.+.}-{3:3}, at: deferred_grow_zone+0x140/0x278 > #2: ffff800084acf600 (rcu_read_lock){....}-{1:3}, at: rt_spin_lock+0x1b4/0x408 > CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: G W 6.19.0-rc6-test #1 PREEMPT_{RT,(full) > } > Tainted: [W]=WARN > Call trace: > show_stack+0x20/0x38 (C) > dump_stack_lvl+0xdc/0xf8 > dump_stack+0x1c/0x28 > __might_resched+0x384/0x530 > deferred_init_memmap_chunk+0x560/0x688 > deferred_grow_zone+0x190/0x278 > _deferred_grow_zone+0x18/0x30 > get_page_from_freelist+0x780/0xf78 > __alloc_frozen_pages_noprof+0x1dc/0x348 > alloc_slab_page+0x30/0x110 > allocate_slab+0x98/0x2a0 > new_slab+0x4c/0x80 > ___slab_alloc+0x5a4/0x770 > __slab_alloc.constprop.0+0x88/0x1e0 > __kmalloc_node_noprof+0x2c0/0x598 > __sdt_alloc+0x3b8/0x728 > build_sched_domains+0xe0/0x1260 > sched_init_domains+0x14c/0x1c8 > sched_init_smp+0x9c/0x1d0 > kernel_init_freeable+0x218/0x358 > kernel_init+0x28/0x208 > ret_from_fork+0x10/0x20 > > Fix it adding a new argument to deferred_init_memmap_chunk() to > explicitly tell it if cond_resched() is allowed or not instead of > relying on some current state information which may vary depending > on the exact kernel configuration options that are enabled. > > Fixes: 3acb913c9d5b ("mm/mm_init: use deferred_init_memmap_chunk() in deferred_grow_zone()") > Suggested-by: Sebastian Andrzej Siewior > Signed-off-by: Waiman Long Reviewed-by: Mike Rapoport (Microsoft) -- Sincerely yours, Mike.