On Mon, Aug 09, 2021 at 12:06:41PM -0700, Guenter Roeck wrote: > On Tue, Aug 03, 2021 at 09:42:18AM +0300, Mike Rapoport wrote: > > From: Mike Rapoport <rppt@xxxxxxxxxxxxx> > > > > 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@xxxxxxxxxxxxx> > > 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. It looks like this change uncovered a problem in x86::memory_map_top_down(). The allocation in alloc_low_pages() is limited by min_pfn_mapped and max_pfn_mapped. The min_pfn_mapped is updated at every iteration of the loop in memory_map_top_down, but there is another loop in init_range_memory_mapping() that maps several regions below the current min_pfn_mapped without updating this variable. The memory layout in qemu with 256M of RAM and EFI enabled, causes exhaustion of the memory limited by min_pfn_mapped and max_pfn_mapped before min_pfn_mapped is updated. Before this commit there was unconditional "reservation" of 2M in the end of the memory that moved the initial min_pfn_mapped below the memory reserved by EFI. The addition of check for xen_domain() removed this reservation for !XEN and made alloc_low_pages() use the range already busy with EFI data. The patch below moves the update of min_pfn_mapped near the update of max_pfn_mapped so that every time a new range is mapped both limits will be updated accordingly. diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 1152a29ce109..be279f6e5a0a 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -1,3 +1,4 @@ +#define DEBUG #include <linux/gfp.h> #include <linux/initrd.h> #include <linux/ioport.h> @@ -485,6 +486,7 @@ static void add_pfn_range_mapped(unsigned long start_pfn, unsigned long end_pfn) nr_pfn_mapped = clean_sort_range(pfn_mapped, E820_MAX_ENTRIES); max_pfn_mapped = max(max_pfn_mapped, end_pfn); + min_pfn_mapped = min(min_pfn_mapped, start_pfn); if (start_pfn < (1UL<<(32-PAGE_SHIFT))) max_low_pfn_mapped = max(max_low_pfn_mapped, @@ -643,7 +645,6 @@ static void __init memory_map_top_down(unsigned long map_start, mapped_ram_size += init_range_memory_mapping(start, last_start); last_start = start; - min_pfn_mapped = last_start >> PAGE_SHIFT; if (mapped_ram_size >= step_size) step_size = get_new_step_size(step_size); } > 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 -- Sincerely yours, Mike.
