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kho: init new_physxa->phys_bits to fix lockdep

Patch series "Several KHO Hotfixes".

Three unrelated fixes for Kexec Handover.


This patch (of 3):

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);

Link: https://lkml.kernel.org/r/20250808201804.772010-2-pasha.tatashin@soleen.com
Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

authored by

Pasha Tatashin and committed by
Andrew Morton 63b17b65 c17b750b

+24 -4
+24 -4
kernel/kexec_handover.c
··· 144 144 unsigned int order) 145 145 { 146 146 struct kho_mem_phys_bits *bits; 147 - struct kho_mem_phys *physxa; 147 + struct kho_mem_phys *physxa, *new_physxa; 148 148 const unsigned long pfn_high = pfn >> order; 149 149 150 150 might_sleep(); 151 151 152 - physxa = xa_load_or_alloc(&track->orders, order, sizeof(*physxa)); 153 - if (IS_ERR(physxa)) 154 - return PTR_ERR(physxa); 152 + physxa = xa_load(&track->orders, order); 153 + if (!physxa) { 154 + int err; 155 + 156 + new_physxa = kzalloc(sizeof(*physxa), GFP_KERNEL); 157 + if (!new_physxa) 158 + return -ENOMEM; 159 + 160 + xa_init(&new_physxa->phys_bits); 161 + physxa = xa_cmpxchg(&track->orders, order, NULL, new_physxa, 162 + GFP_KERNEL); 163 + 164 + err = xa_err(physxa); 165 + if (err || physxa) { 166 + xa_destroy(&new_physxa->phys_bits); 167 + kfree(new_physxa); 168 + 169 + if (err) 170 + return err; 171 + } else { 172 + physxa = new_physxa; 173 + } 174 + } 155 175 156 176 bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS, 157 177 sizeof(*bits));