79d16a84ea
commit daf60d6cca26e50d65dac374db92e58de745ad26 upstream. The call stack shown below is a scenario in the Linux 4.19 kernel. Allocating memory failed where exfat fs use kmalloc_array due to system memory fragmentation, while the u-disk was inserted without recognition. Devices such as u-disk using the exfat file system are pluggable and may be insert into the system at any time. However, long-term running systems cannot guarantee the continuity of physical memory. Therefore, it's necessary to address this issue. Binder:2632_6: page allocation failure: order:4, mode:0x6040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) Call trace: [242178.097582] dump_backtrace+0x0/0x4 [242178.097589] dump_stack+0xf4/0x134 [242178.097598] warn_alloc+0xd8/0x144 [242178.097603] __alloc_pages_nodemask+0x1364/0x1384 [242178.097608] kmalloc_order+0x2c/0x510 [242178.097612] kmalloc_order_trace+0x40/0x16c [242178.097618] __kmalloc+0x360/0x408 [242178.097624] load_alloc_bitmap+0x160/0x284 [242178.097628] exfat_fill_super+0xa3c/0xe7c [242178.097635] mount_bdev+0x2e8/0x3a0 [242178.097638] exfat_fs_mount+0x40/0x50 [242178.097643] mount_fs+0x138/0x2e8 [242178.097649] vfs_kern_mount+0x90/0x270 [242178.097655] do_mount+0x798/0x173c [242178.097659] ksys_mount+0x114/0x1ac [242178.097665] __arm64_sys_mount+0x24/0x34 [242178.097671] el0_svc_common+0xb8/0x1b8 [242178.097676] el0_svc_handler+0x74/0x90 [242178.097681] el0_svc+0x8/0x340 By analyzing the exfat code,we found that continuous physical memory is not required here,so kvmalloc_array is used can solve this problem. Cc: stable@vger.kernel.org Signed-off-by: gaoming <gaoming20@hihonor.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.