問題：メモリ割り当ての問題
私のプラットフォーム：
SOC = STM32H743 (ARMv7E-M | Cortex-M7)
Board = Waveshare CoreH7XXI
Linux Kernel = 5.8.10 (stable 2020-09-17)
initial defconfig file = stm32_defconfig
rootfs = built using busybox | busybox compiled using arm-linux-gnueabihf-gcc as FDPIC ELF
私は次のようにrootfsを一度作成しました。このガイド私はFDPIC ELF（arm_cortex-mシリーズのようなmmuを持たないプラットフォームのための場所に依存しないelf）でコンパイルするように直接設定し、もう1つはbuildroot（ツールチェーン、rootfs、カーネル）を使って構築しました。
しかし、それはうまくいきませんでした。私のカーネルはどのファイルも実行できません。私のrootfsの/linuxrcまたは/sbin/initにあるinitファイルも実行できません（ビジボックスバイナリへのシンボリックリンクであることを知っています）。最初の段落で述べたように、他の実行可能形式（FDPIC ELFとBFLT（フラットバイナリ）を意味します）を試しましたが、そのうちの何も動作せず、カーネルで次のことを意味errno -12するエラーが発生しました。十分な保存。
これは私のカーネルログです。 log_levelは7です。
Starting kernel ...
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Linux version 5.7.19 (root@Mahyar1284) (gcc version 9.3.0 (Buildroot 2020.08), GNU ld (GNU Binutils) 2.32) #3 PREEMPT Sun Oct 11 08:20:09 +0330 2020
[ 0.000000] CPU: ARMv7-M [411fc271] revision 1 (ARMv7M), cr=00000000
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache
[ 0.000000] OF: fdt: Machine model: Waveshare STM32H743i-Coreh7 board
[ 0.000000] Built 1 zonelists, mobility grouping off. Total pages: 1937
[ 0.000000] Kernel command line: console=ttySTM0,115200n8 root=/dev/mmcblk0p2 rw rootwait loglevel=7 init=/linuxrc
[ 0.000000] Dentry cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 5136K/7812K available (1517K kernel code, 142K rwdata, 556K rodata, 72K init, 114K bss, 2676K reserved, 0K cma-reserved)
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[ 0.866164] VFS: Mounted root (ext4 filesystem) on device 179:2.
[ 0.875365] devtmpfs: mounted
[ 0.879076] Freeing unused kernel memory: 72K
[ 0.883567] This architecture does not have kernel memory protection.
[ 0.889882] Run /linuxrc as init process
[ 0.902632] random: fast init done
[ 0.911679] linuxrc: page allocation failure: order:8, mode:0xcc0(GFP_KERNEL), nodemask=(null)
[ 0.922278] nommu: Allocation of length 675840 from process 1 (linuxrc) failed
[ 0.929778] binfmt_flat: Unable to allocate RAM for process text/data, errno -12
[ 0.937629] Kernel panic - not syncing: Requested init /linuxrc failed (error -12).
[ 0.945187] ---[ end Kernel panic - not syncing: Requested init /linuxrc failed (error -12). ]---
ロギングにデバッグレベル17を使用します。
[ 1.019849] Run /linuxrc as init process
[ 1.023842] with arguments:
[ 1.026661] /linuxrc
[ 1.029174] with environment:
[ 1.032436] HOME=/
[ 1.034646] TERM=linux
[ 1.052238] linuxrc: page allocation failure: order:8, mode:0xcc0(GFP_KERNEL), nodemask=(null)
[ 1.060781] CPU: 0 PID: 1 Comm: linuxrc Not tainted 5.8.10 #41
[ 1.066932] Hardware name: STM32 (Device Tree Support)
[ 1.072346] [<d000b3fd>] (unwind_backtrace) from [<d000a527>] (show_stack+0xb/0xc)
[ 1.079832] [<d000a527>] (show_stack) from [<d0056421>] (warn_alloc+0x63/0xe2)
[ 1.087242] [<d0056421>] (warn_alloc) from [<d00567e9>] (__alloc_pages_nodemask+0x33b/0x55a)
[ 1.095743] [<d00567e9>] (__alloc_pages_nodemask) from [<d0056a17>] (__get_free_pages+0xf/0x24)
[ 2.108641] [<d0056a17>] (__get_free_pages) from [<d0056c9f>] (alloc_pages_exact+0x33/0x44)
[ 2.117162] [<d0056c9f>] (alloc_pages_exact) from [<d0054025>] (do_mmap+0x46f/0x5aa)
[ 2.124999] [<d0054025>] (do_mmap) from [<d004f47b>] (vm_mmap_pgoff+0x5d/0x86)
[ 2.132321] [<d004f47b>] (vm_mmap_pgoff) from [<d008bbdb>] (load_flat_file+0x39b/0x5dc)
[ 2.140215] [<d008bbdb>] (load_flat_file) from [<d008bfe9>] (load_flat_binary+0x49/0x2dc)
[ 2.148593] [<d008bfe9>] (load_flat_binary) from [<d00614c1>] (__do_execve_file+0x439/0x584)
[ 2.157129] [<d00614c1>] (__do_execve_file) from [<d0061b03>] (do_execve+0x17/0x1a)
[ 2.164892] [<d0061b03>] (do_execve) from [<d0184965>] (kernel_init+0x41/0xa0)
[ 2.172212] [<d0184965>] (kernel_init) from [<d00082ad>] (ret_from_fork+0x11/0x24)
[ 2.179638] Exception stack(0xd0435fb0 to 0xd0435ff8)
[ 2.184861] 5fa0: 00000000 00000000 00000000 00000000
[ 2.193055] 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.201091] 5fe0: 00000000 00000000 00000000 00000000 00000000 00000000
[ 2.207831] Mem-Info:
[ 2.210012] active_anon:0 inactive_anon:0 isolated_anon:0
[ 2.210012] active_file:6 inactive_file:11 isolated_file:0
[ 2.210012] unevictable:0 dirty:1 writeback:0
[ 2.210012] slab_reclaimable:26 slab_unreclaimable:339
[ 2.210012] mapped:0 shmem:0 pagetables:0 bounce:0
[ 2.210012] free:580 free_pcp:0 free_cma:0
[ 2.239767] Node 0 active_anon:0kB inactive_anon:0kB active_file:24kB inactive_file:44kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:4kB writeback:0kB shmem:0kB writeback_tmp:0kB all_unreclaimable? no
[ 2.259994] Normal free:2320kB min:284kB low:352kB high:420kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:24kB inactive_file:44kB unevictable:0kB writepending:4kB present:7812kB managed:5188kB mlocked:0kB kernel_stack:200kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
[ 2.287792] lowmem_reserve[]: 0 0
[ 2.290982] Normal: 10*4kB (UM) 5*8kB (UM) 4*16kB (UM) 6*32kB (UM) 1*64kB (M) 3*128kB (UM) 2*256kB (M) 2*512kB (UM) 0*1024kB 0*2048kB 0*4096kB = 2320kB
[ 2.304689] 17 total pagecache pages
[ 2.308111] 1953 pages RAM
[ 2.310798] 0 pages HighMem/MovableOnly
[ 2.314765] 656 pages reserved
[ 2.317682] nommu: Allocation of length 675840 from process 1 (linuxrc) failed
[ 2.325066] active_anon:0 inactive_anon:0 isolated_anon:0
[ 2.325066] active_file:6 inactive_file:11 isolated_file:0
[ 2.325066] unevictable:0 dirty:1 writeback:0
[ 2.325066] slab_reclaimable:26 slab_unreclaimable:339
[ 2.325066] mapped:0 shmem:0 pagetables:0 bounce:0
[ 2.325066] free:580 free_pcp:0 free_cma:0
[ 2.354738] Node 0 active_anon:0kB inactive_anon:0kB active_file:24kB inactive_file:44kB unevictable:0kB isolated(anon):0kB isolated(file):0kB mapped:0kB dirty:4kB writeback:0kB shmem:0kB writeback_tmp:0kB all_unreclaimable? no
[ 2.374960] Normal free:2320kB min:284kB low:352kB high:420kB reserved_highatomic:0KB active_anon:0kB inactive_anon:0kB active_file:24kB inactive_file:44kB unevictable:0kB writepending:4kB present:7812kB managed:5188kB mlocked:0kB kernel_stack:200kB pagetables:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
[ 2.402754] lowmem_reserve[]: 0 0
[ 2.405941] Normal: 10*4kB (UM) 5*8kB (UM) 4*16kB (UM) 6*32kB (UM) 1*64kB (M) 3*128kB (UM) 2*256kB (M) 2*512kB (UM) 0*1024kB 0*2048kB 0*4096kB = 2320kB
[ 2.419639] 17 total pagecache pages
[ 2.423247] binfmt_flat: Unable to allocate RAM for process text/data, errno -12
[ 2.430708] Kernel panic - not syncing: Requested init /linuxrc failed (error -12).
[ 2.438253] ---[ end Kernel panic - not syncing: Requested init /linuxrc failed (error -12). ]---
修正する:
GDB + OpenOCDを使用してカーネルをデバッグしましたが、binfmt_flat.cファイルラインでエラーが見つかりました634。 ::
pr_err("Unable to allocate RAM for process text/data, " "errno %d\n", ret);
memp = realdatastart;
memp_size = len;
} else {
len = text_len + data_len + extra + MAX_SHARED_LIBS * sizeof(u32);
len = PAGE_ALIGN(len);
textpos = vm_mmap(NULL, 0, len,
PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);
if (!textpos || IS_ERR_VALUE(textpos)) {
ret = textpos;
if (!textpos)
ret = -ENOMEM;
pr_err("Unable to allocate RAM for process text/data, "
"errno %d\n", ret);
goto err;
}
textpos = vm_mmap(NULL, 0, len, PROT_READ | PROT_EXEC | PROT_WRITE, MAP_PRIVATE, 0);vm_mmap関数（）で問題が発生したようです。
unsigned long vm_mmap(struct file *file, unsigned long addr,
unsigned long len, unsigned long prot,
unsigned long flag, unsigned long offset)
{
if (unlikely(offset + PAGE_ALIGN(len) < offset))
return -EINVAL;
if (unlikely(offset_in_page(offset)))
return -EINVAL;
return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT);
}