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Subject[PATCH, 3.18] sleeping function called from invalid context
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With 3.18, I was seeing a significant number of allocation warnings
from load_elf_binary call paths [1].

Allocating FPU state atomically [2] does prevent potentially sleeping
while atomic, but probably isn't the correct fix. Anyone familiar with
this area?

-- [1]

BUG: sleeping function called from invalid context at mm/slub.c:1240
in_atomic(): 1, irqs_disabled(): 0, pid: 29016, name: dmesg
INFO: lockdep is turned off.
Preemption disabled at:[<ffffffff8114625f>] handle_mm_fault+0x5ff/0x8a0

CPU: 122 PID: 29016 Comm: dmesg Tainted: G W 3.18.0-test #6
Hardware name: Supermicro AS -1042G-LTF/H8QGL, BIOS DS3.5a 11/13/2014
ffffffff8203b81b ffff886fdf62f888 ffffffff81b942e8 0000000000000007
0000000000000000 ffff886fdf62f8b8 ffffffff8109ac4c 0000000000000000
0000000000000010 ffff8807df84bc00 00000000000000d0 ffff886fdf62f908
Call Trace:
[<ffffffff81b942e8>] dump_stack+0x4f/0x7c
[<ffffffff8109ac4c>] __might_sleep+0x164/0x250
[<ffffffff8116372b>] kmem_cache_alloc+0xeb/0x138
[<ffffffff8100e0e1>] init_fpu+0x71/0xb0
[<ffffffff81003966>] math_state_restore+0xce/0x208
[<ffffffff8100437b>] do_device_not_available+0x2b/0x60
[<ffffffff81ba70f5>] device_not_available+0x15/0x20
[<ffffffff81487102>] ? copy_page+0x12/0x33
[<ffffffff8109edb9>] ? get_parent_ip+0x11/0x58
[<ffffffff8109ee55>] ? preempt_count_add+0x55/0xb0
[<ffffffff811437a1>] ? do_cow_fault+0xe9/0x258
[<ffffffff8114625f>] handle_mm_fault+0x5ff/0x8a0
[<ffffffff81032218>] ? __do_page_fault+0xc8/0x498
[<ffffffff811481b9>] ? vma_gap_callbacks_rotate+0x19/0x20
[<ffffffff8103227d>] __do_page_fault+0x12d/0x498
[<ffffffff810b682e>] ? up_write+0x1e/0x48
[<ffffffff81148d18>] ? vma_link+0x80/0xc0
[<ffffffff81149cb2>] ? vma_set_page_prot+0x3a/0x60
[<ffffffff8114ae6e>] ? mmap_region+0x1be/0x5e0
[<ffffffff8103262e>] do_page_fault+0x1e/0x70
[<ffffffff81ba737f>] page_fault+0x1f/0x30
[<ffffffff81487f3e>] ? __clear_user+0x2e/0x50
[<ffffffff81487f22>] ? __clear_user+0x12/0x50
[<ffffffff81487f8a>] clear_user+0x2a/0x30
[<ffffffff811ca1e1>] padzero+0x21/0x30
[<ffffffff811cc41f>] load_elf_binary+0x8cf/0xdd0
[<ffffffff8117d18f>] search_binary_handler+0x7f/0x1f8
[<ffffffff8117ec06>] do_execve_common.isra.34+0x616/0x790
[<ffffffff8117eb62>] ? do_execve_common.isra.34+0x572/0x790
[<ffffffff8117ed93>] do_execve+0x13/0x18
[<ffffffff8117f070>] SyS_execve+0x20/0x30
[<ffffffff81ba6159>] stub_execve+0x69/0xa0

-- [2]

diff --git a/arch/x86/include/asm/fpu-internal.h
b/arch/x86/include/asm/fpu-internal.h
index e97622f..57029ad 100644
--- a/arch/x86/include/asm/fpu-internal.h
+++ b/arch/x86/include/asm/fpu-internal.h
@@ -574,7 +574,7 @@ static inline int fpu_alloc(struct fpu *fpu)
{
if (fpu_allocated(fpu))
return 0;
- fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_KERNEL);
+ fpu->state = kmem_cache_alloc(task_xstate_cachep, GFP_ATOMIC);
if (!fpu->state)
return -ENOMEM;
WARN_ON((unsigned long)fpu->state & 15);
--
Daniel J Blueman

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