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Fredric Cover
ecf3107bfa
commit806c00c23eupstream. Currently in smb3_simple_fallocate_range(), a 1 MB buffer is allocated using kzalloc(). Under heavy memory fragmentation, a contiguous 1 MB block of physical memory (an order-8 allocation) may not be available, causing the allocation to fail. This failure was observed during xfstests generic/013 on a 4GB RAM test machine running fsstress: fsstress: page allocation failure: order:8, mode:0x40dc0(GFP_KERNEL|__GFP_ZERO|__GFP_COMP), nodemask=(null),cpuset=/,mems_allowed=0 Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 warn_alloc+0x163/0x190 __alloc_pages_slowpath.constprop.0+0x71b/0x12f0 __alloc_frozen_pages_noprof+0x2f6/0x340 alloc_pages_mpol+0xb6/0x170 ___kmalloc_large_node+0xb3/0xd0 __kmalloc_large_noprof+0x1e/0xc0 smb3_simple_falloc.isra.0+0x62b/0x960 cifs_fallocate+0xed/0x180 vfs_fallocate+0x165/0x3c0 __x64_sys_fallocate+0x48/0xa0 do_syscall_64+0xe1/0x640 entry_SYSCALL_64_after_hwframe+0x76/0x7e </TASK> Node 0 Normal: 3375*4kB ... 7*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB Since this scratch buffer does not require physically contiguous memory, switch the allocation to kvzalloc(). This retains the performance benefits of kmalloc() under normal conditions, while gracefully falling back to virtually contiguous memory when physical allocation fails. Fixes:966a3cb7c7("cifs: improve fallocate emulation") Cc: stable@vger.kernel.org Signed-off-by: Fredric Cover <fredric.cover.lkernel@gmail.com> Tested-by: Fredric Cover <fredric.cover.lkernel@gmail.com> Signed-off-by: Steve French <stfrench@microsoft.com> 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.