Re: [PATCH] mm: Fix memblock_free_late() when using deferred struct page

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Tue, 2026-02-10 at 12:04 +1100, Benjamin Herrenschmidt wrote:
> On Fri, 2026-02-06 at 12:33 +0200, Mike Rapoport wrote:
> > 
> > So it essentially becomes "oneliner" :)
> > 
> > diff --git a/mm/memblock.c b/mm/memblock.c
> > index e76255e4ff36..6e984bcdf6cd 100644
> > --- a/mm/memblock.c
> > +++ b/mm/memblock.c
> > @@ -1770,10 +1770,8 @@ void __init memblock_free_late(phys_addr_t
> > base, phys_addr_t size)
> >  	cursor = PFN_UP(base);
> >  	end = PFN_DOWN(base + size);
> >  
> > -	for (; cursor < end; cursor++) {
> > -		memblock_free_pages(pfn_to_page(cursor), cursor,
> > 0);
> > -		totalram_pages_inc();
> > -	}
> > +	for (; cursor < end; cursor++)
> > +		free_reserved_page(pfn_to_page(cursor));
> >  }
> 
> Nice and sweet :-)
> 
> I'll spin that & test it and send a v2. Thanks !

Tadaaa ! Looks like I'll need to dig deeper... Busy with something else
today but I'll get back to this asap.

[    0.076840] BUG: unable to handle page fault for address: ffffce1a005a0788
[    0.078226] #PF: supervisor read access in kernel mode
[    0.078226] #PF: error_code(0x0000) - not-present page
[    0.078226] PGD 0 P4D 0 
[    0.078226] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
[    0.078226] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.12.68-92.123.amzn2023.x86_64 #1
[    0.078226] Hardware name: Amazon EC2 t3a.nano/, BIOS 1.0 10/16/2017
[    0.078226] RIP: 0010:__list_del_entry_valid_or_report+0x32/0xb0
[    0.078226] Code: 89 fe 48 85 d2 74 3e 48 85 c9 74 47 48 b8 00 01 00 00 00 00 ad de 48 39 c2 74 46 48 b8 22 01 00 00 00 00 ad de 48 39 c1 74 45 <4c> 8b 01 49 39 f8 75 4e 4c 8b 4a 08 4d 39 c1 75 56 b8 01 00 00 00
[    0.078226] RSP: 0000:ffffffff9ac03cc0 EFLAGS: 00010006
[    0.078226] RAX: dead000000000122 RBX: fffff56600459c80 RCX: ffffce1a005a0788
[    0.078226] RDX: ffffce1a005e3e08 RSI: fffff56600459c88 RDI: fffff56600459c88
[    0.078226] RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
[    0.078226] R10: 000000000000001c R11: 0000000000000200 R12: ffff8ca75bacbc80
[    0.078226] R13: 0000000000000000 R14: 0000000000011673 R15: fffff56600459cc0
[    0.078226] FS:  0000000000000000(0000) GS:ffff8ca752c00000(0000) knlGS:0000000000000000
[    0.078226] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.078226] CR2: ffffce1a005a0788 CR3: 0000000006c34000 CR4: 00000000003506f0
[    0.078226] Call Trace:
[    0.078226]  <TASK>
[    0.078226]  __free_one_page+0x170/0x520
[    0.078226]  free_pcppages_bulk+0x151/0x1e0
[    0.078226]  free_unref_page_commit+0x263/0x320
[    0.078226]  free_unref_page+0x2c8/0x5b0
[    0.078226]  ? srso_return_thunk+0x5/0x5f
[    0.078226]  free_reserved_page+0x1c/0x30
[    0.078226]  memblock_free_late+0x6c/0xc0
[    0.078226]  efi_free_boot_services+0x11f/0x2e0
[    0.078226]  __efi_enter_virtual_mode+0x181/0x210
[    0.078226]  efi_enter_virtual_mode+0xcd/0x110
[    0.078226]  start_kernel+0x393/0x500
[    0.078226]  x86_64_start_reservations+0x14/0x30
[    0.078226]  x86_64_start_kernel+0x77/0x80
[    0.078226]  common_startup_64+0x13e/0x141
[    0.078226]  </TASK>
[    0.078226] Modules linked in:
[    0.078226] CR2: ffffce1a005a0788
[    0.078226] ---[ end trace 0000000000000000 ]---
[    0.078226] RIP: 0010:__list_del_entry_valid_or_report+0x32/0xb0
[    0.078226] Code: 89 fe 48 85 d2 74 3e 48 85 c9 74 47 48 b8 00 01 00 00 00 00 ad de 48 39 c2 74 46 48 b8 22 01 00 00 00 00 ad de 48 39 c1 74 45 <4c> 8b 01 49 39 f8 75 4e 4c 8b 4a 08 4d 39 c1 75 56 b8 01 00 00 00
[    0.078226] RSP: 0000:ffffffff9ac03cc0 EFLAGS: 00010006
[    0.078226] RAX: dead000000000122 RBX: fffff56600459c80 RCX: ffffce1a005a0788
[    0.078226] RDX: ffffce1a005e3e08 RSI: fffff56600459c88 RDI: fffff56600459c88
[    0.078226] RBP: 0000000000000000 R08: ffffffffffffffc0 R09: 0000000000000000
[    0.078226] R10: 000000000000001c R11: 0000000000000200 R12: ffff8ca75bacbc80
[    0.078226] R13: 0000000000000000 R14: 0000000000011673 R15: fffff56600459cc0
[    0.078226] FS:  0000000000000000(0000) GS:ffff8ca752c00000(0000) knlGS:0000000000000000
[    0.078226] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.078226] CR2: ffffce1a005a0788 CR3: 0000000006c34000 CR4: 00000000003506f0
[    0.078226] Kernel panic - not syncing: Fatal exception
[    0.078226] ---[ end Kernel panic - not syncing: Fatal exception ]---