linux-kernel - Re: [PATCH v2 01/32] kho: init new_physxa->phys

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aIdNTN1qd0dTvsQm@kernel.org>
Date: Mon, 28 Jul 2025 13:13:32 +0300
From: Mike Rapoport <rppt@...nel.org>
To: Pasha Tatashin <pasha.tatashin@...een.com>
Cc: pratyush@...nel.org, jasonmiu@...gle.com, graf@...zon.com,
	changyuanl@...gle.com, dmatlack@...gle.com, rientjes@...gle.com,
	corbet@....net, rdunlap@...radead.org,
	ilpo.jarvinen@...ux.intel.com, kanie@...ux.alibaba.com,
	ojeda@...nel.org, aliceryhl@...gle.com, masahiroy@...nel.org,
	akpm@...ux-foundation.org, tj@...nel.org, yoann.congal@...le.fr,
	mmaurer@...gle.com, roman.gushchin@...ux.dev, chenridong@...wei.com,
	axboe@...nel.dk, mark.rutland@....com, jannh@...gle.com,
	vincent.guittot@...aro.org, hannes@...xchg.org,
	dan.j.williams@...el.com, david@...hat.com,
	joel.granados@...nel.org, rostedt@...dmis.org,
	anna.schumaker@...cle.com, song@...nel.org, zhangguopeng@...inos.cn,
	linux@...ssschuh.net, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-mm@...ck.org,
	gregkh@...uxfoundation.org, tglx@...utronix.de, mingo@...hat.com,
	bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
	hpa@...or.com, rafael@...nel.org, dakr@...nel.org,
	bartosz.golaszewski@...aro.org, cw00.choi@...sung.com,
	myungjoo.ham@...sung.com, yesanishhere@...il.com,
	Jonathan.Cameron@...wei.com, quic_zijuhu@...cinc.com,
	aleksander.lobakin@...el.com, ira.weiny@...el.com,
	andriy.shevchenko@...ux.intel.com, leon@...nel.org, lukas@...ner.de,
	bhelgaas@...gle.com, wagi@...nel.org, djeffery@...hat.com,
	stuart.w.hayes@...il.com, ptyadav@...zon.de, lennart@...ttering.net,
	brauner@...nel.org, linux-api@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, saeedm@...dia.com,
	ajayachandra@...dia.com, jgg@...dia.com, parav@...dia.com,
	leonro@...dia.com, witu@...dia.com
Subject: Re: [PATCH v2 01/32] kho: init new_physxa->phys_bits to fix lockdep

On Wed, Jul 23, 2025 at 02:46:14PM +0000, Pasha Tatashin wrote:
> Lockdep shows the following warning:
> 
> INFO: trying to register non-static key.
> The code is fine but needs lockdep annotation, or maybe
> you didn't initialize this object before use?
> turning off the locking correctness validator.
> 
> [<ffffffff810133a6>] dump_stack_lvl+0x66/0xa0
> [<ffffffff8136012c>] assign_lock_key+0x10c/0x120
> [<ffffffff81358bb4>] register_lock_class+0xf4/0x2f0
> [<ffffffff813597ff>] __lock_acquire+0x7f/0x2c40
> [<ffffffff81360cb0>] ? __pfx_hlock_conflict+0x10/0x10
> [<ffffffff811707be>] ? native_flush_tlb_global+0x8e/0xa0
> [<ffffffff8117096e>] ? __flush_tlb_all+0x4e/0xa0
> [<ffffffff81172fc2>] ? __kernel_map_pages+0x112/0x140
> [<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
> [<ffffffff81359556>] lock_acquire+0xe6/0x280
> [<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
> [<ffffffff8100b9e0>] _raw_spin_lock+0x30/0x40
> [<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
> [<ffffffff813ec327>] xa_load_or_alloc+0x67/0xe0
> [<ffffffff813eb4c0>] kho_preserve_folio+0x90/0x100
> [<ffffffff813ebb7f>] __kho_finalize+0xcf/0x400
> [<ffffffff813ebef4>] kho_finalize+0x34/0x70
> 
> This is becase xa has its own lock, that is not initialized in
> xa_load_or_alloc.
> 
> Modifiy __kho_preserve_order(), to properly call
> xa_init(&new_physxa->phys_bits);
> 
> Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
> Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
> ---
>  kernel/kexec_handover.c | 29 +++++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c
> index 5a21dbe17950..1ff6b242f98c 100644
> --- a/kernel/kexec_handover.c
> +++ b/kernel/kexec_handover.c
> @@ -144,14 +144,35 @@ static int __kho_preserve_order(struct kho_mem_track *track, unsigned long pfn,
>  				unsigned int order)
>  {
>  	struct kho_mem_phys_bits *bits;
> -	struct kho_mem_phys *physxa;
> +	struct kho_mem_phys *physxa, *new_physxa;
>  	const unsigned long pfn_high = pfn >> order;
>  
>  	might_sleep();
>  
> -	physxa = xa_load_or_alloc(&track->orders, order, sizeof(*physxa));
> -	if (IS_ERR(physxa))
> -		return PTR_ERR(physxa);
> +	physxa = xa_load(&track->orders, order);
> +	if (!physxa) {
> +		new_physxa = kzalloc(sizeof(*physxa), GFP_KERNEL);
> +		if (!new_physxa)
> +			return -ENOMEM;
> +
> +		xa_init(&new_physxa->phys_bits);
> +		physxa = xa_cmpxchg(&track->orders, order, NULL, new_physxa,
> +				    GFP_KERNEL);
> +		if (xa_is_err(physxa)) {
> +			int err_ret = xa_err(physxa);

Just int err should be fine here, otherwise

Acked-by: Mike Rapoport (Microsoft) <rppt@...nel.org>

> +
> +			xa_destroy(&new_physxa->phys_bits);
> +			kfree(new_physxa);
> +
> +			return err_ret;
> +		}
> +		if (physxa) {
> +			xa_destroy(&new_physxa->phys_bits);
> +			kfree(new_physxa);
> +		} else {
> +			physxa = new_physxa;
> +		}
> +	}
>  
>  	bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS,
>  				sizeof(*bits));
> -- 
> 2.50.0.727.gbf7dc18ff4-goog
> 

-- 
Sincerely yours,
Mike.