natebrune/fmem

Linux Kernel Module designed to help analyze volatile memory in the linux kernel

I am Nate Brune, bio is wip.

fmem's Issues

failed to insmod fmem.ko

Hi, get a problem when i use fmem.
My machine info:

zhanged@dcu:~/code/kmd/fmem$ cat /proc/version
Linux version 5.0.0-23-generic (buildd@lgw01-amd64-030) (gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)) #24~18.04.1-Ubuntu SMP Mon Jul 29 16:12:28 UTC 2019
zhanged@dcu:~/code/kmd/fmem$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.3 LTS
Release:	18.04
Codename:	bionic
zhanged@dcu:~/code/kmd/fmem$

The dmesg output:

[272256.188917] fmem init_module 463: init
[272256.188918] fmem find_symbols 453: set guess_page_is_ram: 00000000e03dff47
[272256.188927] sysfs: cannot create duplicate filename '/devices/virtual/fmem'
[272256.188929] CPU: 1 PID: 4609 Comm: insmod Tainted: G           OE     5.0.0-23-generic #24~18.04.1-Ubuntu
[272256.188929] Hardware name: System manufacturer System Product Name/PRIME Z390-A, BIOS 1401 11/26/2019
[272256.188930] Call Trace:
[272256.188934]  dump_stack+0x63/0x85
[272256.188935]  sysfs_warn_dup+0x5b/0x70
[272256.188936]  sysfs_create_dir_ns+0xbe/0xd0
[272256.188937]  kobject_add_internal+0xac/0x2b0
[272256.188939]  ? kfree_const+0x22/0x30
[272256.188940]  kobject_add+0x71/0xd0
[272256.188942]  ? _cond_resched+0x19/0x40
[272256.188943]  ? kmem_cache_alloc_trace+0x1a6/0x1c0
[272256.188946]  get_device_parent.isra.29+0x1ad/0x1d0
[272256.188946]  device_add+0xed/0x6b0
[272256.188947]  device_create_groups_vargs+0xe4/0xf0
[272256.188949]  ? 0xffffffffc0b93000
[272256.188950]  device_create+0x49/0x60
[272256.188951]  ? __class_create+0x54/0x80
[272256.188952]  ? 0xffffffffc0b93000
[272256.188953]  init_module+0xc2/0x1000 [fmem]
[272256.188955]  do_one_initcall+0x4a/0x1c9
[272256.188956]  ? _cond_resched+0x19/0x40
[272256.188957]  ? kmem_cache_alloc_trace+0x42/0x1c0
[272256.188958]  do_init_module+0x5f/0x216
[272256.188959]  load_module+0x19f6/0x20a0
[272256.188961]  __do_sys_finit_module+0xfc/0x120
[272256.188962]  ? __do_sys_finit_module+0xfc/0x120
[272256.188963]  __x64_sys_finit_module+0x1a/0x20
[272256.188964]  do_syscall_64+0x5a/0x120
[272256.188965]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[272256.188966] RIP: 0033:0x7f051602d959
[272256.188967] Code: 00 f3 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ff f4 2c 00 f7 d8 64 89 01 48
[272256.188968] RSP: 002b:00007fff7eb7ac08 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[272256.188969] RAX: ffffffffffffffda RBX: 000055a62e142780 RCX: 00007f051602d959
[272256.188969] RDX: 0000000000000000 RSI: 000055a62e142260 RDI: 0000000000000003
[272256.188969] RBP: 000055a62e142260 R08: 0000000000000000 R09: 0000000000000000
[272256.188970] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
[272256.188970] R13: 000055a62e1423a0 R14: 0000000000000000 R15: 000055a62e142260
[272256.188971] kobject_add_internal failed for fmem with -EEXIST, don't try to register things with the same name in the same directory.

compile error on ARM

On an ARM 64 system with kernel 5.3.18-24.52, make runs into this issue (sorry for the missing newlines - I did not find out how I get newlines in code block working yet):

ccuser01@aarch64-arm-cc-niap:~/mem/fmem-master> make rm -f *.o *.ko *.mod.c Module.symvers Module.markers modules.order \.*.o.cmd \.*.ko.cmd \.*.o.d rm -rf \.tmp_versions make -C /lib/modules/uname -r/build KBUILD_EXTMOD=pwdmodules make[1]: Entering directory '/usr/src/linux-5.3.18-24.52-obj/arm64/default' CC [M] /home/ccuser01/mem/fmem-master/lkm.o /home/ccuser01/mem/fmem-master/lkm.c: In function ‘my_xlate_dev_mem_ptr’: /home/ccuser01/mem/fmem-master/lkm.c:99:25: **error: implicit declaration of function ‘ioremap_cache’**; did you mean ‘node_add_cache’? [-Werror=implicit-function-declaration] addr = (void __force *)ioremap_cache(start, PAGE_SIZE); ^~~~~~~~~~~~~ node_add_cache /home/ccuser01/mem/fmem-master/lkm.c:99:9: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] addr = (void __force *)ioremap_cache(start, PAGE_SIZE); ^ /home/ccuser01/mem/fmem-master/lkm.c: In function ‘my_unxlate_dev_mem_ptr’: /home/ccuser01/mem/fmem-master/lkm.c:124:2: error: implicit declaration of function ‘iounmap’; did you mean ‘kunmap’? [-Werror=implicit-function-declaration] iounmap((void __iomem *)((unsigned long)addr & PAGE_MASK)); ^~~~~~~ kunmap cc1: some warnings being treated as errors make[3]: *** [/usr/src/linux-5.3.18-24.52/scripts/Makefile.build:282: /home/ccuser01/mem/fmem-master/lkm.o] Error 1 make[2]: *** [/usr/src/linux-5.3.18-24.52/Makefile:1650: _module_/home/ccuser01/mem/fmem-master] Error 2 make[1]: *** [../../../linux-5.3.18-24.52/Makefile:179: sub-make] Error 2 make[1]: Leaving directory '/usr/src/linux-5.3.18-24.52-obj/arm64/default' make: *** [Makefile:12: fmem] Error 2 ccuser01@aarch64-arm-cc-niap:~/mem/fmem-master> uname -a Linux aarch64-arm-cc-niap 5.3.18-24.52-default #1 SMP Tue Mar 2 13:15:25 UTC 2021 (c35b124) aarch64 aarch64 aarch64 GNU/Linux ccuser01@aarch64-arm-cc-niap:~/mem/fmem-master>

And just the error from above:
/home/ccuser01/mem/fmem-master/lkm.c:99:25: error: implicit declaration of function ‘ioremap_cache’; did you mean ‘node_add_cache’? [-Werror=implicit-function-declaration]
addr = (void __force *)ioremap_cache(start, PAGE_SIZE);
^~~~~~~~~~~~~
node_add_cache

Unable to compile on - IBM AIX architecture

Hi Team,

I am getting an error as mentioned below, on running the make command as it is unable to compile

make: Cannot find a rule to create target = from dependencies.

Looking forward to your answer
Cheers,

Can't compile on Ubuntu 16.04

FYI, I'm unable to compile fmem on Ubuntu 16.04 with kernel 4.13 :

$ make
rm -f *.o *.ko *.mod.c Module.symvers Module.markers modules.order \.*.o.cmd \.*.ko.cmd \.*.o.d
rm -rf \.tmp_versions
make -C /lib/modules/`uname -r`/build SUBDIRS=`pwd` modules
make[1]: Entering directory '/usr/src/linux-headers-4.13.0-36-generic'
  CC [M]  /home/christophetd/fmem-master/lkm.o
/home/christophetd/fmem-master/lkm.c: In function ‘memory_lseek’:
/home/christophetd/fmem-master/lkm.c:289:42: error: ‘struct inode’ has no member named ‘i_mutex’
  mutex_lock(&file->f_path.dentry->d_inode->i_mutex);
                                          ^
/home/christophetd/fmem-master/lkm.c:310:44: error: ‘struct inode’ has no member named ‘i_mutex’
  mutex_unlock(&file->f_path.dentry->d_inode->i_mutex);
                                            ^
scripts/Makefile.build:308: recipe for target '/home/christophetd/fmem-master/lkm.o' failed
make[2]: *** [/home/christophetd/fmem-master/lkm.o] Error 1
Makefile:1550: recipe for target '_module_/home/christophetd/fmem-master' failed
make[1]: *** [_module_/home/christophetd/fmem-master] Error 2
make[1]: Leaving directory '/usr/src/linux-headers-4.13.0-36-generic'
Makefile:12: recipe for target 'fmem' failed
make: *** [fmem] Error 2

no symbol version for module_layout. Module.symvers present.

Can't install fmem on Centos 6.3 any assistance would be greatly appreciated

Make Output:

rm -f .o .ko .mod.c Module.symvers Module.markers modules.order ..o.cmd ..ko.cmd ..o.d
rm -rf .tmp_versions
make -C /lib/modules/uname -r/build KBUILD_EXTMOD=pwd modules
make[1]: Entering directory /usr/src/kernels/2.6.32-279.el6.x86_64' CC [M] /root/Documents/fmem/lkm.o Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix gcc version 4.4.7 20120313 (Red Hat 4.4.7-23) (GCC) COLLECT_GCC_OPTIONS='-nostdinc' '-isystem' '/usr/lib/gcc/x86_64-redhat-linux/4.4.7/include' '-Iinclude' '-I/usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include' '-include' 'include/linux/autoconf.h' '-D__KERNEL__' '-Wall' '-Wundef' '-Wstrict-prototypes' '-Wno-trigraphs' '-fno-strict-aliasing' '-fno-common' '-Werror-implicit-function-declaration' '-Wno-format-security' '-fno-delete-null-pointer-checks' '-O2' '-m64' '-mtune=generic' '-mno-red-zone' '-mcmodel=kernel' '-funit-at-a-time' '-maccumulate-outgoing-args' '-fstack-protector' '-DCONFIG_AS_CFI=1' '-DCONFIG_AS_CFI_SIGNAL_FRAME=1' '-pipe' '-Wno-sign-compare' '-fno-asynchronous-unwind-tables' '-mno-sse' '-mno-mmx' '-mno-sse2' '-mno-3dnow' '-Wframe-larger-than=2048' '-Wno-unused-but-set-variable' '-fno-omit-frame-pointer' '-fno-optimize-sibling-calls' '-g' '-pg' '-Wdeclaration-after-statement' '-Wno-pointer-sign' '-fno-strict-overflow' '-fno-dwarf2-cfi-asm' '-fconserve-stack' '-v' '-DMODULE' '-DKBUILD_STR(s)=#s' '-DKBUILD_BASENAME=KBUILD_STR(lkm)' '-DKBUILD_MODNAME=KBUILD_STR(fmem)' '-DDEBUG_HASH=50' '-DDEBUG_HASH2=5' '-c' '-o' '/root/Documents/fmem/.tmp_lkm.o' /usr/libexec/gcc/x86_64-redhat-linux/4.4.7/cc1 -quiet -nostdinc -v -Iinclude -I/usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include -D__KERNEL__ -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DMODULE -DKBUILD_STR(s)=#s -DKBUILD_BASENAME=KBUILD_STR(lkm) -DKBUILD_MODNAME=KBUILD_STR(fmem) -DDEBUG_HASH=50 -DDEBUG_HASH2=5 -isystem /usr/lib/gcc/x86_64-redhat-linux/4.4.7/include -include include/linux/autoconf.h -MD /root/Documents/fmem/.lkm.o.d /root/Documents/fmem/lkm.c -quiet -dumpbase lkm.c -m64 -mtune=generic -mno-red-zone -mcmodel=kernel -maccumulate-outgoing-args -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -auxbase-strip /root/Documents/fmem/.tmp_lkm.o -g -O2 -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -Werror-implicit-function-declaration -Wno-format-security -Wno-sign-compare -Wframe-larger-than=2048 -Wno-unused-but-set-variable -Wdeclaration-after-statement -Wno-pointer-sign -version -p -fno-strict-aliasing -fno-common -fno-delete-null-pointer-checks -funit-at-a-time -fstack-protector -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -fno-optimize-sibling-calls -fno-strict-overflow -fno-dwarf2-cfi-asm -fconserve-stack -o - | as -V -Qy --64 -o /root/Documents/fmem/.tmp_lkm.o - #include "..." search starts here: #include <...> search starts here: include /usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include /usr/lib/gcc/x86_64-redhat-linux/4.4.7/include End of search list. GNU C (GCC) version 4.4.7 20120313 (Red Hat 4.4.7-23) (x86_64-redhat-linux) compiled by GNU C version 4.4.7 20120313 (Red Hat 4.4.7-23), GMP version 4.3.1, MPFR version 2.4.1. GNU assembler version 2.20.51.0.2 (x86_64-redhat-linux) using BFD version version 2.20.51.0.2-5.48.el6_10.1 20100205 GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: f1e04b41791fd0c9eea88d5989031e7d COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/ LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-nostdinc' '-isystem' '/usr/lib/gcc/x86_64-redhat-linux/4.4.7/include' '-Iinclude' '-I/usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include' '-include' 'include/linux/autoconf.h' '-D__KERNEL__' '-Wall' '-Wundef' '-Wstrict-prototypes' '-Wno-trigraphs' '-fno-strict-aliasing' '-fno-common' '-Werror-implicit-function-declaration' '-Wno-format-security' '-fno-delete-null-pointer-checks' '-O2' '-m64' '-mtune=generic' '-mno-red-zone' '-mcmodel=kernel' '-funit-at-a-time' '-maccumulate-outgoing-args' '-fstack-protector' '-DCONFIG_AS_CFI=1' '-DCONFIG_AS_CFI_SIGNAL_FRAME=1' '-pipe' '-Wno-sign-compare' '-fno-asynchronous-unwind-tables' '-mno-sse' '-mno-mmx' '-mno-sse2' '-mno-3dnow' '-Wframe-larger-than=2048' '-Wno-unused-but-set-variable' '-fno-omit-frame-pointer' '-fno-optimize-sibling-calls' '-g' '-pg' '-Wdeclaration-after-statement' '-Wno-pointer-sign' '-fno-strict-overflow' '-fno-dwarf2-cfi-asm' '-fconserve-stack' '-v' '-DMODULE' '-DKBUILD_STR(s)=#s' '-DKBUILD_BASENAME=KBUILD_STR(lkm)' '-DKBUILD_MODNAME=KBUILD_STR(fmem)' '-DDEBUG_HASH=50' '-DDEBUG_HASH2=5' '-c' '-o' '/root/Documents/fmem/.tmp_lkm.o' LD [M] /root/Documents/fmem/fmem.o Building modules, stage 2. MODPOST 1 modules CC /root/Documents/fmem/fmem.mod.o Using built-in specs. Target: x86_64-redhat-linux Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-bootstrap --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-1.5.0.0/jre --enable-libgcj-multifile --enable-java-maintainer-mode --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --disable-libjava-multilib --with-ppl --with-cloog --with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux Thread model: posix gcc version 4.4.7 20120313 (Red Hat 4.4.7-23) (GCC) COLLECT_GCC_OPTIONS='-nostdinc' '-isystem' '/usr/lib/gcc/x86_64-redhat-linux/4.4.7/include' '-Iinclude' '-I/usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include' '-include' 'include/linux/autoconf.h' '-D__KERNEL__' '-Wall' '-Wundef' '-Wstrict-prototypes' '-Wno-trigraphs' '-fno-strict-aliasing' '-fno-common' '-Werror-implicit-function-declaration' '-Wno-format-security' '-fno-delete-null-pointer-checks' '-O2' '-m64' '-mtune=generic' '-mno-red-zone' '-mcmodel=kernel' '-funit-at-a-time' '-maccumulate-outgoing-args' '-fstack-protector' '-DCONFIG_AS_CFI=1' '-DCONFIG_AS_CFI_SIGNAL_FRAME=1' '-pipe' '-Wno-sign-compare' '-fno-asynchronous-unwind-tables' '-mno-sse' '-mno-mmx' '-mno-sse2' '-mno-3dnow' '-Wframe-larger-than=2048' '-Wno-unused-but-set-variable' '-fno-omit-frame-pointer' '-fno-optimize-sibling-calls' '-g' '-pg' '-Wdeclaration-after-statement' '-Wno-pointer-sign' '-fno-strict-overflow' '-fno-dwarf2-cfi-asm' '-fconserve-stack' '-v' '-DKBUILD_STR(s)=#s' '-DKBUILD_BASENAME=KBUILD_STR(fmem.mod)' '-DKBUILD_MODNAME=KBUILD_STR(fmem)' '-DDEBUG_HASH=50' '-DDEBUG_HASH2=5' '-DMODULE' '-c' '-o' '/root/Documents/fmem/fmem.mod.o' /usr/libexec/gcc/x86_64-redhat-linux/4.4.7/cc1 -quiet -nostdinc -v -Iinclude -I/usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include -D__KERNEL__ -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DKBUILD_STR(s)=#s -DKBUILD_BASENAME=KBUILD_STR(fmem.mod) -DKBUILD_MODNAME=KBUILD_STR(fmem) -DDEBUG_HASH=50 -DDEBUG_HASH2=5 -DMODULE -isystem /usr/lib/gcc/x86_64-redhat-linux/4.4.7/include -include include/linux/autoconf.h -MD /root/Documents/fmem/.fmem.mod.o.d /root/Documents/fmem/fmem.mod.c -quiet -dumpbase fmem.mod.c -m64 -mtune=generic -mno-red-zone -mcmodel=kernel -maccumulate-outgoing-args -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -auxbase-strip /root/Documents/fmem/fmem.mod.o -g -O2 -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -Werror-implicit-function-declaration -Wno-format-security -Wno-sign-compare -Wframe-larger-than=2048 -Wno-unused-but-set-variable -Wdeclaration-after-statement -Wno-pointer-sign -version -p -fno-strict-aliasing -fno-common -fno-delete-null-pointer-checks -funit-at-a-time -fstack-protector -fno-asynchronous-unwind-tables -fno-omit-frame-pointer -fno-optimize-sibling-calls -fno-strict-overflow -fno-dwarf2-cfi-asm -fconserve-stack -o - | as -V -Qy --64 -o /root/Documents/fmem/fmem.mod.o - #include "..." search starts here: #include <...> search starts here: include /usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include /usr/lib/gcc/x86_64-redhat-linux/4.4.7/include End of search list. GNU C (GCC) version 4.4.7 20120313 (Red Hat 4.4.7-23) (x86_64-redhat-linux) compiled by GNU C version 4.4.7 20120313 (Red Hat 4.4.7-23), GMP version 4.3.1, MPFR version 2.4.1. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 GNU assembler version 2.20.51.0.2 (x86_64-redhat-linux) using BFD version version 2.20.51.0.2-5.48.el6_10.1 20100205 Compiler executable checksum: f1e04b41791fd0c9eea88d5989031e7d COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/:/usr/libexec/gcc/x86_64-redhat-linux/4.4.7/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/ LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/4.4.7/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-nostdinc' '-isystem' '/usr/lib/gcc/x86_64-redhat-linux/4.4.7/include' '-Iinclude' '-I/usr/src/kernels/2.6.32-279.el6.x86_64/arch/x86/include' '-include' 'include/linux/autoconf.h' '-D__KERNEL__' '-Wall' '-Wundef' '-Wstrict-prototypes' '-Wno-trigraphs' '-fno-strict-aliasing' '-fno-common' '-Werror-implicit-function-declaration' '-Wno-format-security' '-fno-delete-null-pointer-checks' '-O2' '-m64' '-mtune=generic' '-mno-red-zone' '-mcmodel=kernel' '-funit-at-a-time' '-maccumulate-outgoing-args' '-fstack-protector' '-DCONFIG_AS_CFI=1' '-DCONFIG_AS_CFI_SIGNAL_FRAME=1' '-pipe' '-Wno-sign-compare' '-fno-asynchronous-unwind-tables' '-mno-sse' '-mno-mmx' '-mno-sse2' '-mno-3dnow' '-Wframe-larger-than=2048' '-Wno-unused-but-set-variable' '-fno-omit-frame-pointer' '-fno-optimize-sibling-calls' '-g' '-pg' '-Wdeclaration-after-statement' '-Wno-pointer-sign' '-fno-strict-overflow' '-fno-dwarf2-cfi-asm' '-fconserve-stack' '-v' '-DKBUILD_STR(s)=#s' '-DKBUILD_BASENAME=KBUILD_STR(fmem.mod)' '-DKBUILD_MODNAME=KBUILD_STR(fmem)' '-DDEBUG_HASH=50' '-DDEBUG_HASH2=5' '-DMODULE' '-c' '-o' '/root/Documents/fmem/fmem.mod.o' LD [M] /root/Documents/fmem/fmem.ko.unsigned NO SIGN [M] /root/Documents/fmem/fmem.ko make[1]: Leaving directory /usr/src/kernels/2.6.32-279.el6.x86_64'

Installed Packages

[root@centos-6 fmem]# yum list installed | grep kernel
abrt-addon-kerneloops.x86_64
dracut-kernel.noarch 004-283.el6 @anaconda-CentOS-201207061011.x86_64/6.3
kernel.x86_64 2.6.32-279.el6 @anaconda-CentOS-201207061011.x86_64/6.3
kernel-devel.x86_64 2.6.32-279.el6 @/kernel-devel-2.6.32-279.el6.x86_64
kernel-firmware.noarch 2.6.32-279.el6 @anaconda-CentOS-201207061011.x86_64/6.3
kernel-headers.x86_64 2.6.32-279.el6 @/kernel-headers-2.6.32-279.el6.x86_64
libreport-plugin-kerneloops.x86_64

uname

[root@centos-6 fmem]# uname -a
Linux centos-6.3 2.6.32-279.el6.x86_64 #1 SMP Fri Jun 22 12:19:21 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

Modules.symvers

[root@centos-6 2.6.32-279.el6.x86_64]# ls
arch drivers include kernel Makefile.common Module.symvers scripts System.map virt
block firmware init lib mm net security tools
crypto fs ipc Makefile modules.order samples sound usr

CentOS kernel 5.1.14 error

[root@test-01 fmem]# make 
rm -f *.o *.ko *.mod.c Module.symvers Module.markers modules.order \.*.o.cmd \.*.ko.cmd \.*.o.d
rm -rf \.tmp_versions
make -C /lib/modules/`uname -r`/build SUBDIRS=`pwd` modules
make[1]: Entering directory `/usr/src/kernels/5.1.14-1.el7.elrepo.x86_64'
/usr/src/kernels/5.1.14-1.el7.elrepo.x86_64/Makefile:205: ================= WARNING ================
/usr/src/kernels/5.1.14-1.el7.elrepo.x86_64/Makefile:206: 'SUBDIRS' will be removed after Linux 5.3
/usr/src/kernels/5.1.14-1.el7.elrepo.x86_64/Makefile:207: Please use 'M=' or 'KBUILD_EXTMOD' instead
/usr/src/kernels/5.1.14-1.el7.elrepo.x86_64/Makefile:208: ==========================================
  CC [M]  /root/fmem/lkm.o
/root/fmem/lkm.c:32:27: fatal error: linux/bootmem.h: No such file or directory
 #include <linux/bootmem.h>
                           ^
compilation terminated.
make[3]: *** [/root/fmem/lkm.o] Error 1
make[2]: *** [_module_/root/fmem] Error 2
make[1]: *** [sub-make] Error 2
make[1]: Leaving directory `/usr/src/kernels/5.1.14-1.el7.elrepo.x86_64'
make: *** [fmem] Error 2
[root@test-01 fmem]# uname -a 
Linux test-01 5.1.14-1.el7.elrepo.x86_64 #1 SMP Sat Jun 22 08:30:29 EDT 2019 x86_64 x86_64 x86_64 GNU/Linux
[root@test-01 fmem]# cat /etc/redhat-release 
CentOS Linux release 7.4.1708 (Core) 

Issue creating /dev/fmem (unable to get major 241 for memory devs)

After running ./run.sh I get the following output in my dmesg log. I tried changing FMEM_MAJOR to a different number, this solved my issue.

My kernel knowledge is insufficient to add the dynamic allocation.

[ 8337.184174] fmem init_module 450: init                                                                                                                   
[ 8337.184175] fmem find_symbols 440: set guess_page_is_ram: 0000000048c62be7
[ 8337.184176] unable to get major 241 for memory devs
[ 8337.184204] sysfs: cannot create duplicate filename '/dev/char/241:1'
[ 8337.184174] fmem init_module 450: init                                                                                                                   
[ 8337.184175] fmem find_symbols 440: set guess_page_is_ram: 0000000048c62be7
[ 8337.184176] unable to get major 241 for memory devs
[ 8337.184204] sysfs: cannot create duplicate filename '/dev/char/241:1'
 8337.184205] CPU: 12 PID: 22083 Comm: insmod Tainted: P           OE     4.18.0-25-generic #26-Ubuntu
[ 8337.184205] Hardware name: System76 Serval WS/Serval WS, BIOS 1.05.20 01/21/2019
[ 8337.184206] Call Trace:
[ 8337.184210]  dump_stack+0x63/0x8a
[ 8337.184212]  sysfs_warn_dup.cold.4+0x17/0x32
[ 8337.184214]  sysfs_do_create_link_sd.isra.2+0xa8/0xc0
[ 8337.184216]  sysfs_create_link+0x25/0x40
[ 8337.184219]  device_add+0x5a2/0x650
[ 8337.184221]  device_create_groups_vargs+0xd8/0xf0
[ 8337.184223]  ? 0xffffffffc221a000
[ 8337.184224]  device_create+0x49/0x60
[ 8337.184225]  ? __class_create+0x51/0x90
[ 8337.184226]  ? 0xffffffffc221a000
[ 8337.184227]  ? kobject_uevent_env+0x114/0x7b0
[ 8337.184230]  init_module+0x9a/0x1000 [fmem]
[ 8337.184233]  do_one_initcall+0x4a/0x1c4
[ 8337.184236]  ? free_pcp_prepare+0x4f/0xd0
[ 8337.184237]  ? _cond_resched+0x19/0x30
[ 8337.184240]  ? kmem_cache_alloc_trace+0x165/0x1d0
[ 8337.184241]  ? do_init_module+0x27/0x220
[ 8337.184243]  do_init_module+0x60/0x220
[ 8337.184244]  load_module+0x14e6/0x1880
[ 8337.184246]  __do_sys_finit_module+0xbd/0x120
[ 8337.184247]  ? __do_sys_finit_module+0xbd/0x120
[ 8337.184248]  __x64_sys_finit_module+0x1a/0x20
[ 8337.184250]  do_syscall_64+0x5a/0x110
[ 8337.184251]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 8337.184252] RIP: 0033:0x7f9ff4ed6219
[ 8337.184252] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
 f0 ff ff 73 01 c3 48 8b 0d 47 fc 0c 00 f7 d8 64 89 01 48 
[ 8337.184271] RSP: 002b:00007ffc08ad2a38 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[ 8337.184272] RAX: ffffffffffffffda RBX: 00005587ce62d820 RCX: 00007f9ff4ed6219
[ 8337.184272] RDX: 0000000000000000 RSI: 00005587ce62d260 RDI: 0000000000000003
[ 8337.184273] RBP: 00005587ce62d260 R08: 0000000000000000 R09: 0000000000000000
[ 8337.184273] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
[ 8337.184274] R13: 00005587ce62d7e0 R14: 0000000000000000 R15: 00005587ce62d260
[ 8422.640015] fmem cleanup_module 464: destroying fmem device
[ 8422.640034] fmem cleanup_module 471: exit
[ 8456.651323] fmem init_module 455: init
[ 8456.651324] fmem find_symbols 445: set guess_page_is_ram: 0000000048c62be7
[ 8456.651325] unable to get major 241 for memory devs
[ 8456.651358] sysfs: cannot create duplicate filename '/dev/char/241:1'
[ 8456.651359] CPU: 3 PID: 22838 Comm: insmod Tainted: P           OE     4.18.0-25-generic #26-Ubuntu
[ 8456.651360] Hardware name: System76 Serval WS/Serval WS, BIOS 1.05.20 01/21/2019
[ 8456.651361] Call Trace:
[ 8456.651364]  dump_stack+0x63/0x8a
[ 8456.651365]  sysfs_warn_dup.cold.4+0x17/0x32
[ 8456.651366]  sysfs_do_create_link_sd.isra.2+0xa8/0xc0
[ 8456.651367]  sysfs_create_link+0x25/0x40
[ 8456.651369]  device_add+0x5a2/0x650
[ 8456.651370]  device_create_groups_vargs+0xd8/0xf0
[ 8456.651371]  ? 0xffffffffc221a000
[ 8456.651372]  device_create+0x49/0x60
[ 8456.651373]  ? __class_create+0x51/0x90
[ 8456.651373]  ? 0xffffffffc221a000
[ 8456.651374]  ? kobject_uevent_env+0x114/0x7b0
[ 8456.651375]  init_module+0x9a/0x1000 [fmem]
[ 8456.651377]  do_one_initcall+0x4a/0x1c4
[ 8456.651379]  ? free_pcp_prepare+0x4f/0xd0
[ 8456.651380]  ? _cond_resched+0x19/0x30
[ 8456.651381]  ? kmem_cache_alloc_trace+0x165/0x1d0
[ 8456.651382]  ? do_init_module+0x27/0x220
[ 8456.651383]  do_init_module+0x60/0x220
[ 8456.651383]  load_module+0x14e6/0x1880
[ 8456.651385]  __do_sys_finit_module+0xbd/0x120
[ 8456.651385]  ? __do_sys_finit_module+0xbd/0x120
[ 8456.651386]  __x64_sys_finit_module+0x1a/0x20
[ 8456.651387]  do_syscall_64+0x5a/0x110
[ 8456.651388]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 8456.651389] RIP: 0033:0x7f0f0a138219
[ 8456.651389] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
 f0 ff ff 73 01 c3 48 8b 0d 47 fc 0c 00 f7 d8 64 89 01 48 
[ 8456.651400] RSP: 002b:00007ffe02e582d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[ 8456.651401] RAX: ffffffffffffffda RBX: 0000556b56645820 RCX: 00007f0f0a138219
[ 8456.651401] RDX: 0000000000000000 RSI: 0000556b56645260 RDI: 0000000000000003
[ 8456.651401] RBP: 0000556b56645260 R08: 0000000000000000 R09: 0000000000000000
[ 8456.651402] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
[ 8456.651402] R13: 0000556b566457e0 R14: 0000000000000000 R15: 0000556b56645260
[ 8503.465302] fmem cleanup_module 469: destroying fmem device
[ 8503.465322] fmem cleanup_module 476: exit