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In vn_io_fault1(), reduce the scope where pagefaults are disabled.

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Most important for the future use, do not call
vm_fault_quick_hold_pages() with disabled pagefaults.

Reported and tested by:	pho (as part of the larger patch)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2018-03-24 13:13:52 +00:00
parent a37d4032ed
commit 161bf65f8a
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=331487
1 changed files with 16 additions and 11 deletions
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27
sys/kern/vfs_vnops.c
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@ -956,23 +956,30 @@ static int
vn_io_fault_doio(struct vn_io_fault_args *args, struct uio *uio,
struct thread *td)
{
int error, save;
error = 0;
save = vm_fault_disable_pagefaults();
switch (args->kind) {
case VN_IO_FAULT_FOP:
return ((args->args.fop_args.doio)(args->args.fop_args.fp,
uio, args->cred, args->flags, td));
error = (args->args.fop_args.doio)(args->args.fop_args.fp,
uio, args->cred, args->flags, td);
break;
case VN_IO_FAULT_VOP:
if (uio->uio_rw == UIO_READ) {
return (VOP_READ(args->args.vop_args.vp, uio,
args->flags, args->cred));
error = VOP_READ(args->args.vop_args.vp, uio,
args->flags, args->cred);
} else if (uio->uio_rw == UIO_WRITE) {
return (VOP_WRITE(args->args.vop_args.vp, uio,
args->flags, args->cred));
error = VOP_WRITE(args->args.vop_args.vp, uio,
args->flags, args->cred);
}
break;
default:
panic("vn_io_fault_doio: unknown kind of io %d %d",
args->kind, uio->uio_rw);
}
panic("vn_io_fault_doio: unknown kind of io %d %d", args->kind,
uio->uio_rw);
vm_fault_enable_pagefaults(save);
return (error);
}
static int
@ -1047,7 +1054,7 @@ vn_io_fault1(struct vnode *vp, struct uio *uio, struct vn_io_fault_args *args,
vm_offset_t addr, end;
size_t len, resid;
ssize_t adv;
int error, cnt, save, saveheld, prev_td_ma_cnt;
int error, cnt, saveheld, prev_td_ma_cnt;
if (vn_io_fault_prefault) {
error = vn_io_fault_prefault_user(uio);
@ -1073,7 +1080,6 @@ vn_io_fault1(struct vnode *vp, struct uio *uio, struct vn_io_fault_args *args,
short_uio.uio_rw = uio->uio_rw;
short_uio.uio_td = uio->uio_td;
save = vm_fault_disable_pagefaults();
error = vn_io_fault_doio(args, uio, td);
if (error != EFAULT)
goto out;
@ -1144,7 +1150,6 @@ vn_io_fault1(struct vnode *vp, struct uio *uio, struct vn_io_fault_args *args,
td->td_ma_cnt = prev_td_ma_cnt;
curthread_pflags_restore(saveheld);
out:
vm_fault_enable_pagefaults(save);
free(uio_clone, M_IOV);
return (error);
}