Re: [PATCH v3] memblock: make memblock_find_in_range method private

[Guenter Roeck <linux@roeck-us.net>]

On Tue, Aug 03, 2021 at 09:42:18AM +0300, Mike Rapoport wrote:
> From: Mike Rapoport <rppt@linux.ibm.com>
> 
> There are a lot of uses of memblock_find_in_range() along with
> memblock_reserve() from the times memblock allocation APIs did not exist.
> 
> memblock_find_in_range() is the very core of memblock allocations, so any
> future changes to its internal behaviour would mandate updates of all the
> users outside memblock.
> 
> Replace the calls to memblock_find_in_range() with an equivalent calls to
> memblock_phys_alloc() and memblock_phys_alloc_range() and make
> memblock_find_in_range() private method of memblock.
> 
> This simplifies the callers, ensures that (unlikely) errors in
> memblock_reserve() are handled and improves maintainability of
> memblock_find_in_range().
> 
> Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>

I see a number of crashes in next-20210806 when booting x86 images from efi.

[    0.000000] efi: EFI v2.70 by EDK II
[    0.000000] efi: SMBIOS=0x1fbcc000 ACPI=0x1fbfa000 ACPI 2.0=0x1fbfa014 MEMATTR=0x1f25f018
[    0.000000] SMBIOS 2.8 present.
[    0.000000] DMI: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
[    0.000000] last_pfn = 0x1ff50 max_arch_pfn = 0x400000000
[    0.000000] x86/PAT: Configuration [0-7]: WB  WC  UC- UC  WB  WP  UC- WT
[    0.000000] Kernel panic - not syncing: alloc_low_pages: can not alloc memory
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.14.0-rc4-next-20210806 #1
[    0.000000] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
[    0.000000] Call Trace:
[    0.000000]  ? dump_stack_lvl+0x57/0x7d
[    0.000000]  ? panic+0xfc/0x2c6
[    0.000000]  ? alloc_low_pages+0x117/0x156
[    0.000000]  ? phys_pmd_init+0x234/0x342
[    0.000000]  ? phys_pud_init+0x171/0x337
[    0.000000]  ? __kernel_physical_mapping_init+0xec/0x276
[    0.000000]  ? init_memory_mapping+0x1ea/0x2aa
[    0.000000]  ? init_range_memory_mapping+0xdf/0x12e
[    0.000000]  ? init_mem_mapping+0x1e9/0x26f
[    0.000000]  ? setup_arch+0x5ff/0xb6d
[    0.000000]  ? start_kernel+0x71/0x6b4
[    0.000000]  ? secondary_startup_64_no_verify+0xc2/0xcb

Bisect points to this patch. Reverting it fixes the problem. Key seems to
be the amount of memory configured in qemu; the problem is not seen if
there is 1G or more of memory, but it is seen with all test boots with
512M or 256M of memory. It is also seen with almost all 32-bit efi boots.

The problem is not seen when booting without efi.

Guenter

---
Bisect log:

# bad: [da454ebf578f6c542ba9f5b3ddb98db3ede109c1] Add linux-next specific files for 20210809
# good: [36a21d51725af2ce0700c6ebcb6b9594aac658a6] Linux 5.14-rc5
git bisect start 'HEAD' 'v5.14-rc5'
# good: [d22fda64bea5f33000e31e5b7e4ba876bca37436] Merge remote-tracking branch 'crypto/master'
git bisect good d22fda64bea5f33000e31e5b7e4ba876bca37436
# good: [b084da3a98fad27a39ed5ca64106b86df0417851] Merge remote-tracking branch 'irqchip/irq/irqchip-next'
git bisect good b084da3a98fad27a39ed5ca64106b86df0417851
# good: [a5383d1f57190a33c6afc25c62b9907d84ba2bc6] Merge remote-tracking branch 'staging/staging-next'
git bisect good a5383d1f57190a33c6afc25c62b9907d84ba2bc6
# good: [a439da3e6abeb054f4e6b0d37814e762b7340196] Merge remote-tracking branch 'seccomp/for-next/seccomp'
git bisect good a439da3e6abeb054f4e6b0d37814e762b7340196
# bad: [9801f3c0890c7b992b45a5c2afcb16c5cdc8388e] mm/idle_page_tracking: Make PG_idle reusable
git bisect bad 9801f3c0890c7b992b45a5c2afcb16c5cdc8388e
# good: [b4f7f4a9b542836683308d48ffdd18471c6f3e76] lazy-tlb-allow-lazy-tlb-mm-refcounting-to-be-configurable-fix
git bisect good b4f7f4a9b542836683308d48ffdd18471c6f3e76
# good: [e30842a48c36f094271eea0984bb861b49c49c87] mm/vmscan: add 'else' to remove check_pending label
git bisect good e30842a48c36f094271eea0984bb861b49c49c87
# bad: [65300b20a21214fb2043419d4e5da1d9947c6e15] mm/madvise: add MADV_WILLNEED to process_madvise()
git bisect bad 65300b20a21214fb2043419d4e5da1d9947c6e15
# bad: [7348da7a8c244d1a755bc5838b04cb9b1b6ee06c] memblock: make memblock_find_in_range method private
git bisect bad 7348da7a8c244d1a755bc5838b04cb9b1b6ee06c
# good: [98f8c467fe2ba8e553b450b2a3294d69f1f2027f] mm-mempolicy-convert-from-atomic_t-to-refcount_t-on-mempolicy-refcnt-fix
git bisect good 98f8c467fe2ba8e553b450b2a3294d69f1f2027f
# good: [760ded422ebe4f8899905b752d8378c44f2a78f3] mm/memplicy: add page allocation function for MPOL_PREFERRED_MANY policy
git bisect good 760ded422ebe4f8899905b752d8378c44f2a78f3
# good: [fbfa0492d9639b67119d3d94b7a6a3f85e064260] mm/mempolicy: advertise new MPOL_PREFERRED_MANY
git bisect good fbfa0492d9639b67119d3d94b7a6a3f85e064260
# good: [ff6d5759a871883aeea38309fb16d91666179328] mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
git bisect good ff6d5759a871883aeea38309fb16d91666179328
# first bad commit: [7348da7a8c244d1a755bc5838b04cb9b1b6ee06c] memblock: make memblock_find_in_range method private