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b=cXAalaX8cQA5O0FWAdJ/j0E31YxR5hXdxTCgFyDdBG9qJqvKpOvZPH4M9x8F+kCfZ r+aoE8qRe9m8d1lmxMGMNq/iAXbL4zNNsMbeDUWioFnq9LZ8JGxoeIisZR184H2Vxy KV02QokV1S7zjW3gTXjWAtmDLzNQJ8ig68XgQBSk= Date: Wed, 8 Apr 2026 08:32:29 -0700 From: Andrew Morton To: "Salunke, Hrushikesh" Cc: "Vlastimil Babka (SUSE)" , , , , , , , , , , , , "David Hildenbrand" Subject: Re: [PATCH] mm/page_alloc: use batch page clearing in kernel_init_pages() Message-Id: <20260408083229.45d1a083f17484d3b2678855@linux-foundation.org> In-Reply-To: <4e8c218b-ac5e-4674-9e1e-acf750f0a5c8@amd.com> References: <20260408092441.435133-1-hsalunke@amd.com> <22b6ff3c-9d41-4eb0-9beb-cb92f3ada89f@kernel.org> <4e8c218b-ac5e-4674-9e1e-acf750f0a5c8@amd.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: D33B112000D X-Stat-Signature: jhz6nmrasudecynq7y4zd7fq5a861etq X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1775662351-544554 X-HE-Meta: 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 H/7qaHp5 frp/8mrOG9BG+A9OtXMjJinNrgZ0n6bUc+9wfuhwrGxA0t3th+XMWEEsOZLVxmTYFS7k4y1ExqAu9DMUze+O9TOu9jToK+EZE8kEDfNCh3A132HBURMKzViMLlaNeh4VMDBDriYSOo31LGT5E8muugkDfqdMGry/WsAxJ23/KAt441OSLuG7uFtL2MCADoK0gDDGrrT0gav6SqhK89uLm/f+0huoLkiK2H6pkuXKovfF84+SvYYn3W/rP3DlPBYXwHzn2yQvi0dxfr0yYNB2tr8ycj6zln8Wy7X8vOYrav6SUBey6lXHJ64n5zi98uovdzzcw Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 8 Apr 2026 16:14:03 +0530 "Salunke, Hrushikesh" wrote: > kernel_init_pages() runs inside the allocator (post_alloc_hook and > __free_pages_prepare), so it inherits whatever context the caller is in. > Testing with CONFIG_DEBUG_ATOMIC_SLEEP=y and CONFIG_PROVE_LOCKING=y, I > hit this during exit_group() -> exit_mmap() -> __zap_vma_range, where a > page allocation happens while the PTE lock and RCU read lock are held, > making the cond_resched() in the clearing loop illegal: > > [ 1997.353228] BUG: sleeping function called from invalid context at mm/page_alloc.c:1235 > [ 1997.353433] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 19725, name: bash > [ 1997.353572] preempt_count: 1, expected: 0 > [ 1997.353706] RCU nest depth: 1, expected: 0 > [ 1997.353837] 3 locks held by bash/19725: > [ 1997.353839] #0: ff38cd415971e540 (&mm->mmap_lock){++++}-{4:4}, at: exit_mmap+0x6e/0x430 > [ 1997.353850] #1: ffffffffb03d6f60 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x2c/0x220 > [ 1997.353855] #2: ff38cd410deb4618 (ptlock_ptr(ptdesc)#2){+.+.}-{3:3}, at: pte_offset_map_lock+0x92/0x170 > [ 1997.353868] Call Trace: > [ 1997.353870] > [ 1997.353873] dump_stack_lvl+0x91/0xb0 > [ 1997.353877] __might_resched+0x15f/0x290 > [ 1997.353882] kernel_init_pages+0x4b/0xa0 > [ 1997.353886] get_page_from_freelist+0x406/0x1e60 > [ 1997.353895] __alloc_frozen_pages_noprof+0x1d8/0x1730 > [ 1997.353912] alloc_pages_mpol+0xa4/0x190 > [ 1997.353917] alloc_pages_noprof+0x59/0xd0 > [ 1997.353919] get_free_pages_noprof+0x11/0x40 > [ 1997.353921] __tlb_remove_folio_pages_size.isra.0+0x7f/0xe0 > [ 1997.353923] __zap_vma_range+0x1bbd/0x1f40 > [ 1997.353931] unmap_vmas+0xd9/0x1d0 > [ 1997.353934] exit_mmap+0x10a/0x430 > [ 1997.353943] __mmput+0x3d/0x130 > [ 1997.353947] do_exit+0x2a7/0xae0 tlb_next_batch() is (fortunately) using GFP_NOWAIT. Perhaps you can alter your patch to not call the cond_resched() if caller is attempting an atomic allocation.