Joonsoo Kim [Wed, 12 Aug 2020 01:37:34 +0000 (18:37 -0700)]
mm/gup: restrict CMA region by using allocation scope API
We have well defined scope API to exclude CMA region. Use it rather than
manipulating gfp_mask manually. With this change, we can now restore
__GFP_MOVABLE for gfp_mask like as usual migration target allocation. It
would result in that the ZONE_MOVABLE is also searched by page allocator.
For hugetlb, gfp_mask is redefined since it has a regular allocation mask
filter for migration target. __GPF_NOWARN is added to hugetlb gfp_mask
filter since a new user for gfp_mask filter, gup, want to be silent when
allocation fails.
Note that this can be considered as a fix for the commit 9a4e9f3b2d73
("mm: update get_user_pages_longterm to migrate pages allocated from CMA
region"). However, "Fixes" tag isn't added here since it is just
suboptimal but it doesn't cause any problem.
Joonsoo Kim [Wed, 12 Aug 2020 01:37:25 +0000 (18:37 -0700)]
mm/migrate: introduce a standard migration target allocation function
There are some similar functions for migration target allocation. Since
there is no fundamental difference, it's better to keep just one rather
than keeping all variants. This patch implements base migration target
allocation function. In the following patches, variants will be converted
to use this function.
Changes should be mechanical, but, unfortunately, there are some
differences. First, some callers' nodemask is assgined to NULL since NULL
nodemask will be considered as all available nodes, that is,
&node_states[N_MEMORY]. Second, for hugetlb page allocation, gfp_mask is
redefined as regular hugetlb allocation gfp_mask plus __GFP_THISNODE if
user provided gfp_mask has it. This is because future caller of this
function requires to set this node constaint. Lastly, if provided nodeid
is NUMA_NO_NODE, nodeid is set up to the node where migration source
lives. It helps to remove simple wrappers for setting up the nodeid.
Note that PageHighmem() call in previous function is changed to open-code
"is_highmem_idx()" since it provides more readability.
Joonsoo Kim [Wed, 12 Aug 2020 01:37:20 +0000 (18:37 -0700)]
mm/migrate: clear __GFP_RECLAIM to make the migration callback consistent with regular THP allocations
new_page_nodemask is a migration callback and it tries to use a common gfp
flags for the target page allocation whether it is a base page or a THP.
The later only adds GFP_TRANSHUGE to the given mask. This results in the
allocation being slightly more aggressive than necessary because the
resulting gfp mask will contain also __GFP_RECLAIM_KSWAPD. THP
allocations usually exclude this flag to reduce over eager background
reclaim during a high THP allocation load which has been seen during large
mmaps initialization. There is no indication that this is a problem for
migration as well but theoretically the same might happen when migrating
large mappings to a different node. Make the migration callback
consistent with regular THP allocations.
Joonsoo Kim [Wed, 12 Aug 2020 01:37:17 +0000 (18:37 -0700)]
mm/hugetlb: unify migration callbacks
There is no difference between two migration callback functions,
alloc_huge_page_node() and alloc_huge_page_nodemask(), except
__GFP_THISNODE handling. It's redundant to have two almost similar
functions in order to handle this flag. So, this patch tries to remove
one by introducing a new argument, gfp_mask, to
alloc_huge_page_nodemask().
After introducing gfp_mask argument, it's caller's job to provide correct
gfp_mask. So, every callsites for alloc_huge_page_nodemask() are changed
to provide gfp_mask.
Note that it's safe to remove a node id check in alloc_huge_page_node()
since there is no caller passing NUMA_NO_NODE as a node id.
Nick Desaulniers [Wed, 12 Aug 2020 01:37:02 +0000 (18:37 -0700)]
scripts/gdb: fix python 3.8 SyntaxWarning
Fixes the observed warnings:
scripts/gdb/linux/rbtree.py:20: SyntaxWarning: "is" with a literal. Did
you mean "=="?
if node is 0:
scripts/gdb/linux/rbtree.py:36: SyntaxWarning: "is" with a literal. Did
you mean "=="?
if node is 0:
It looks like this is a new warning added in Python 3.8. I've only seen
this once after adding the add-auto-load-safe-path rule to my ~/.gdbinit
for a new tree.
Wei Yongjun [Wed, 12 Aug 2020 01:36:59 +0000 (18:36 -0700)]
kcov: make some symbols static
Fix sparse build warnings:
kernel/kcov.c:99:1: warning:
symbol '__pcpu_scope_kcov_percpu_data' was not declared. Should it be static?
kernel/kcov.c:778:6: warning:
symbol 'kcov_remote_softirq_start' was not declared. Should it be static?
kernel/kcov.c:795:6: warning:
symbol 'kcov_remote_softirq_stop' was not declared. Should it be static?
Marco Elver [Wed, 12 Aug 2020 01:36:56 +0000 (18:36 -0700)]
kcov: unconditionally add -fno-stack-protector to compiler options
Unconditionally add -fno-stack-protector to KCOV's compiler options, as
all supported compilers support the option. This saves a compiler
invocation to determine if the option is supported.
Because Clang does not support -fno-conserve-stack, and
-fno-stack-protector was wrapped in the same cc-option, we were missing
-fno-stack-protector with Clang. Unconditionally adding this option
fixes this for Clang.
rapidio/rio_mport_cdev: use array_size() helper in copy_{from,to}_user()
Use array_size() helper instead of the open-coded version in
copy_{from,to}_user(). These sorts of multiplication factors need to be
wrapped in array_size().
This issue was found with the help of Coccinelle and, audited and fixed
manually.
drivers/rapidio/rio-scan.c: use struct_size() helper
Make use of the struct_size() helper instead of an open-coded version in
order to avoid any potential type mistakes.
Also, while there, use the preferred form for passing a size of a struct.
The alternative form where struct name is spelled out hurts readability
and introduces an opportunity for a bug when the pointer variable type is
changed but the corresponding sizeof that is passed as argument is not.
This issue was found with the help of Coccinelle and, audited and fixed
manually.
kdump: append kernel build-id string to VMCOREINFO
Make kernel GNU build-id available in VMCOREINFO. Having build-id in
VMCOREINFO facilitates presenting appropriate kernel namelist image with
debug information file to kernel crash dump analysis tools. Currently
VMCOREINFO lacks uniquely identifiable key for crash analysis automation.
Regarding if this patch is necessary or matching of linux_banner and
OSRELEASE in VMCOREINFO employed by crash(8) meets the need -- IMO,
build-id approach more foolproof, in most instances it is a cryptographic
hash generated using internal code/ELF bits unlike kernel version string
upon which linux_banner is based that is external to the code. I feel
each is intended for a different purpose. Also OSRELEASE is not suitable
when two different kernel builds from same version with different features
enabled.
Currently for most linux (and non-linux) systems build-id can be extracted
using standard methods for file types such as user mode crash dumps,
shared libraries, loadable kernel modules etc., This is an exception for
linux kernel dump. Having build-id in VMCOREINFO brings some uniformity
for automation tools.
Tyler said:
: I think this is a nice improvement over today's linux_banner approach for
: correlating vmlinux to a kernel dump.
:
: The elf notes parsing in this patch lines up with what is described in in
: the "Notes (Nhdr)" section of the elf(5) man page.
:
: BUILD_ID_MAX is sufficient to hold a sha1 build-id, which is the default
: build-id type today in GNU ld(2). It is also sufficient to hold the
: "fast" build-id, which is the default build-id type today in LLVM lld(2).
Kees Cook [Wed, 12 Aug 2020 01:36:30 +0000 (18:36 -0700)]
exec: move path_noexec() check earlier
The path_noexec() check, like the regular file check, was happening too
late, letting LSMs see impossible execve()s. Check it earlier as well in
may_open() and collect the redundant fs/exec.c path_noexec() test under
the same robustness comment as the S_ISREG() check.
My notes on the call path, and related arguments, checks, etc:
do_open_execat()
struct open_flags open_exec_flags = {
.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
.acc_mode = MAY_EXEC,
...
do_filp_open(dfd, filename, open_flags)
path_openat(nameidata, open_flags, flags)
file = alloc_empty_file(open_flags, current_cred());
do_open(nameidata, file, open_flags)
may_open(path, acc_mode, open_flag)
/* new location of MAY_EXEC vs path_noexec() test */
inode_permission(inode, MAY_OPEN | acc_mode)
security_inode_permission(inode, acc_mode)
vfs_open(path, file)
do_dentry_open(file, path->dentry->d_inode, open)
security_file_open(f)
open()
/* old location of path_noexec() test */
Kees Cook [Wed, 12 Aug 2020 01:36:26 +0000 (18:36 -0700)]
exec: move S_ISREG() check earlier
The execve(2)/uselib(2) syscalls have always rejected non-regular files.
Recently, it was noticed that a deadlock was introduced when trying to
execute pipes, as the S_ISREG() test was happening too late. This was
fixed in commit 73601ea5b7b1 ("fs/open.c: allow opening only regular files
during execve()"), but it was added after inode_permission() had already
run, which meant LSMs could see bogus attempts to execute non-regular
files.
Move the test into the other inode type checks (which already look for
other pathological conditions[1]). Since there is no need to use
FMODE_EXEC while we still have access to "acc_mode", also switch the test
to MAY_EXEC.
Also include a comment with the redundant S_ISREG() checks at the end of
execve(2)/uselib(2) to note that they are present to avoid any mistakes.
My notes on the call path, and related arguments, checks, etc:
do_open_execat()
struct open_flags open_exec_flags = {
.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
.acc_mode = MAY_EXEC,
...
do_filp_open(dfd, filename, open_flags)
path_openat(nameidata, open_flags, flags)
file = alloc_empty_file(open_flags, current_cred());
do_open(nameidata, file, open_flags)
may_open(path, acc_mode, open_flag)
/* new location of MAY_EXEC vs S_ISREG() test */
inode_permission(inode, MAY_OPEN | acc_mode)
security_inode_permission(inode, acc_mode)
vfs_open(path, file)
do_dentry_open(file, path->dentry->d_inode, open)
/* old location of FMODE_EXEC vs S_ISREG() test */
security_file_open(f)
open()
Kees Cook [Wed, 12 Aug 2020 01:36:23 +0000 (18:36 -0700)]
exec: change uselib(2) IS_SREG() failure to EACCES
Patch series "Relocate execve() sanity checks", v2.
While looking at the code paths for the proposed O_MAYEXEC flag, I saw
some things that looked like they should be fixed up.
exec: Change uselib(2) IS_SREG() failure to EACCES
This just regularizes the return code on uselib(2).
exec: Move S_ISREG() check earlier
This moves the S_ISREG() check even earlier than it was already.
exec: Move path_noexec() check earlier
This adds the path_noexec() check to the same place as the
S_ISREG() check.
This patch (of 3):
Change uselib(2)' S_ISREG() error return to EACCES instead of EINVAL so
the behavior matches execve(2), and the seemingly documented value. The
"not a regular file" failure mode of execve(2) is explicitly
documented[1], but it is not mentioned in uselib(2)[2] which does,
however, say that open(2) and mmap(2) errors may apply. The documentation
for open(2) does not include a "not a regular file" error[3], but mmap(2)
does[4], and it is EACCES.
Lepton Wu [Wed, 12 Aug 2020 01:36:20 +0000 (18:36 -0700)]
coredump: add %f for executable filename
The document reads "%e" should be "executable filename" while actually it
could be changed by things like pr_ctl PR_SET_NAME. People who uses "%e"
in core_pattern get surprised when they find out they get thread name
instead of executable filename.
This is either a bug of document or a bug of code. Since the behavior of
"%e" is there for long time, it could bring another surprise for users if
we "fix" the code.
So we just "fix" the document. And more, for users who really need the
"executable filename" in core_pattern, we introduce a new "%f" for the
real executable filename. We already have "%E" for executable path in
kernel, so just reuse most of its code for the new added "%f" format.
Tiezhu Yang [Wed, 12 Aug 2020 01:36:16 +0000 (18:36 -0700)]
test_kmod: avoid potential double free in trigger_config_run_type()
Reset the member "test_fs" of the test configuration after a call of the
function "kfree_const" to a null pointer so that a double memory release
will not be performed.
Tiezhu Yang [Wed, 12 Aug 2020 01:36:08 +0000 (18:36 -0700)]
selftests: kmod: use variable NAME in kmod_test_0001()
Patch series "kmod/umh: a few fixes".
Tiezhu Yang had sent out a patch set with a slew of kmod selftest fixes,
and one patch which modified kmod to return 254 when a module was not
found. This opened up pandora's box about why that was being used for and
low and behold its because when UMH_WAIT_PROC is used we call a
kernel_wait4() call but have never unwrapped the error code. The commit
log for that fix details the rationale for the approach taken. I'd
appreciate some review on that, in particular nfs folks as it seems a case
was never really hit before.
This patch (of 5):
Use the variable NAME instead of "\000" directly in kmod_test_0001().
Helge Deller [Wed, 12 Aug 2020 01:36:04 +0000 (18:36 -0700)]
fs/signalfd.c: fix inconsistent return codes for signalfd4
The kernel signalfd4() syscall returns different error codes when called
either in compat or native mode. This behaviour makes correct emulation
in qemu and testing programs like LTP more complicated.
Fix the code to always return -in both modes- EFAULT for unaccessible user
memory, and EINVAL when called with an invalid signal mask.
VFAT/FAT/MSDOS FILESYSTEM: replace HTTP links with HTTPS ones
Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.
Deterministic algorithm:
For each file:
If not .svg:
For each line:
If doesn't contain `xmlns`:
For each link, `http://[^# ]*(?:\w|/)`:
If neither `gnu\.org/license`, nor `mozilla\.org/MPL`:
If both the HTTP and HTTPS versions
return 200 OK and serve the same content:
Replace HTTP with HTTPS.
The 64 bit ino is being compared to the product of two u32 values,
however, the multiplication is being performed using a 32 bit multiply so
there is a potential of an overflow. To be fully safe, cast uspi->s_ncg
to a u64 to ensure a 64 bit multiplication occurs to avoid any chance of
overflow.
Joe Perches [Wed, 12 Aug 2020 01:35:49 +0000 (18:35 -0700)]
nilfs2: use a more common logging style
Add macros for nilfs_<level>(sb, fmt, ...) and convert the uses of
'nilfs_msg(sb, KERN_<LEVEL>, ...)' to 'nilfs_<level>(sb, ...)' so nilfs2
uses a logging style more like the typical kernel logging style.
Eric Biggers [Wed, 12 Aug 2020 01:35:43 +0000 (18:35 -0700)]
nilfs2: only call unlock_new_inode() if I_NEW
Patch series "nilfs2 updates".
This patch (of 3):
unlock_new_inode() is only meant to be called after a new inode has
already been inserted into the hash table. But nilfs_new_inode() can call
it even before it has inserted the inode, triggering the WARNING in
unlock_new_inode(). Fix this by only calling unlock_new_inode() if the
inode has the I_NEW flag set, indicating that it's in the table.
Eric Biggers [Wed, 12 Aug 2020 01:35:39 +0000 (18:35 -0700)]
fs/minix: remove expected error message in block_to_path()
When truncating a file to a size within the last allowed logical block,
block_to_path() is called with the *next* block. This exceeds the limit,
causing the "block %ld too big" error message to be printed.
This case isn't actually an error; there are just no more blocks past that
point. So, remove this error message.
Eric Biggers [Wed, 12 Aug 2020 01:35:36 +0000 (18:35 -0700)]
fs/minix: fix block limit check for V1 filesystems
The minix filesystem reads its maximum file size from its on-disk
superblock. This value isn't necessarily a multiple of the block size.
When it's not, the V1 block mapping code doesn't allow mapping the last
possible block. Commit 6ed6a722f9ab ("minixfs: fix block limit check")
fixed this in the V2 mapping code. Fix it in the V1 mapping code too.
Eric Biggers [Wed, 12 Aug 2020 01:35:33 +0000 (18:35 -0700)]
fs/minix: set s_maxbytes correctly
The minix filesystem leaves super_block::s_maxbytes at MAX_NON_LFS rather
than setting it to the actual filesystem-specific limit. This is broken
because it means userspace doesn't see the standard behavior like getting
EFBIG and SIGXFSZ when exceeding the maximum file size.
Eric Biggers [Wed, 12 Aug 2020 01:35:30 +0000 (18:35 -0700)]
fs/minix: reject too-large maximum file size
If the minix filesystem tries to map a very large logical block number to
its on-disk location, block_to_path() can return offsets that are too
large, causing out-of-bounds memory accesses when accessing indirect index
blocks. This should be prevented by the check against the maximum file
size, but this doesn't work because the maximum file size is read directly
from the on-disk superblock and isn't validated itself.
Fix this by validating the maximum file size at mount time.
Eric Biggers [Wed, 12 Aug 2020 01:35:27 +0000 (18:35 -0700)]
fs/minix: don't allow getting deleted inodes
If an inode has no links, we need to mark it bad rather than allowing it
to be accessed. This avoids WARNINGs in inc_nlink() and drop_nlink() when
doing directory operations on a fuzzed filesystem.
Eric Biggers [Wed, 12 Aug 2020 01:35:24 +0000 (18:35 -0700)]
fs/minix: check return value of sb_getblk()
Patch series "fs/minix: fix syzbot bugs and set s_maxbytes".
This series fixes all syzbot bugs in the minix filesystem:
KASAN: null-ptr-deref Write in get_block
KASAN: use-after-free Write in get_block
KASAN: use-after-free Read in get_block
WARNING in inc_nlink
KMSAN: uninit-value in get_block
WARNING in drop_nlink
It also fixes the minix filesystem to set s_maxbytes correctly, so that
userspace sees the correct behavior when exceeding the max file size.
Quentin Monnet [Wed, 12 Aug 2020 01:35:13 +0000 (18:35 -0700)]
checkpatch: fix CONST_STRUCT when const_structs.checkpatch is missing
Checkpatch reports warnings when some specific structs are not declared as
const in the code. The list of structs to consider was initially defined
in the checkpatch.pl script itself, but it was later moved to an external
file (scripts/const_structs.checkpatch), in commit bf1fa1dae68e
("checkpatch: externalize the structs that should be const"). This
introduced two minor issues:
- When file scripts/const_structs.checkpatch is not present (for
example, if checkpatch is run outside of the kernel directory with the
"--no-tree" option), a warning is printed to stderr to tell the user
that "No structs that should be const will be found". This is fair,
but the warning is printed unconditionally, even if the option
"--ignore CONST_STRUCT" is passed. In the latter case, we explicitly
ask checkpatch to skip this check, so no warning should be printed.
- When scripts/const_structs.checkpatch is missing, or even when trying
to silence the warning by adding an empty file, $const_structs is set
to "", and the regex used for finding structs that should be const,
"$line =~ /struct\s+($const_structs)(?!\s*\{)/)", matches all
structs found in the code, thus reporting a number of false positives.
Let's fix the first item by skipping scripts/const_structs.checkpatch
processing if "CONST_STRUCT" checks are ignored, and the second one by
skipping the test if $const_structs is not defined. Since we modify the
read_words() function a little bit, update the checks for
$typedefsfile/$typeOtherTypedefs as well.
Kars Mulder [Wed, 12 Aug 2020 01:34:56 +0000 (18:34 -0700)]
kstrto*: do not describe simple_strto*() as obsolete/replaced
The documentation of the kstrto*() functions describes kstrto*() as
"replacements" of the "obsolete" simple_strto*() functions. Both of these
terms are inaccurate: they're not replacements because they have different
behaviour, and the simple_strto*() are not obsolete because there are
cases where they have benefits over kstrto*().
Remove usage of the terms "replacement" and "obsolete" in reference to
simple_strto*(), and instead use the term "preferred over".
Kars Mulder [Wed, 12 Aug 2020 01:34:53 +0000 (18:34 -0700)]
kstrto*: correct documentation references to simple_strto*()
The documentation of the kstrto*() functions reference the simple_strtoull
function by "used as a replacement for [the obsolete] simple_strtoull".
All these functions describes themselves as replacements for the function
simple_strtoull, even though a function like kstrtol() would be more aptly
described as a replacement of simple_strtol().
Fix these references by making the documentation of kstrto*() reference
the closest simple_strto*() equivalent available. The functions
kstrto[u]int() do not have direct simple_strto[u]int() equivalences, so
these are made to refer to simple_strto[u]l() instead.
Furthermore, add parentheses after function names, as is standard in
kernel documentation.
Tiezhu Yang [Wed, 12 Aug 2020 01:34:47 +0000 (18:34 -0700)]
lib/test_lockup.c: fix return value of test_lockup_init()
Since filp_open() returns an error pointer, we should use IS_ERR() to
check the return value and then return PTR_ERR() if failed to get the
actual return value instead of always -EINVAL.
E.g. without this patch:
[root@localhost loongson]# ls no_such_file
ls: cannot access no_such_file: No such file or directory
[root@localhost loongson]# modprobe test_lockup file_path=no_such_file lock_sb_umount time_secs=60 state=S
modprobe: ERROR: could not insert 'test_lockup': Invalid argument
[root@localhost loongson]# dmesg | tail -1
[ 126.100596] test_lockup: cannot find file_path
With this patch:
[root@localhost loongson]# ls no_such_file
ls: cannot access no_such_file: No such file or directory
[root@localhost loongson]# modprobe test_lockup file_path=no_such_file lock_sb_umount time_secs=60 state=S
modprobe: ERROR: could not insert 'test_lockup': Unknown symbol in module, or unknown parameter (see dmesg)
[root@localhost loongson]# dmesg | tail -1
[ 95.134362] test_lockup: failed to open no_such_file: -2
Tiezhu Yang [Wed, 12 Aug 2020 01:34:44 +0000 (18:34 -0700)]
lib/Kconfig.debug: make TEST_LOCKUP depend on module
Since test_lockup is a test module to generate lockups, it is better to
limit TEST_LOCKUP to module (=m) or disabled (=n) because we can not use
the module parameters when CONFIG_TEST_LOCKUP=y.
lib/test_bitops: do the full test during module init
Currently, the bitops test consists of two parts: one part is executed
during module load, the second part during module unload. This is
cumbersome for the user, as he has to perform two steps to execute all
tests, and is different from most (all?) other tests.
Merge the two parts, so both are executed during module load.
struct __genradix is defined as having its member 'root'
annotated as __rcu. But in the corresponding API RCU is not used.
Sparse reports this type mismatch as:
lib/generic-radix-tree.c:56:35: warning: incorrect type in initializer (different address spaces)
lib/generic-radix-tree.c:56:35: expected struct genradix_root *r
lib/generic-radix-tree.c:56:35: got struct genradix_root [noderef] <asn:4> *__val
with 6 other ones.
So, correct root's type by removing this unneeded __rcu.
Stefano Brivio [Wed, 12 Aug 2020 01:34:32 +0000 (18:34 -0700)]
lib/test_bitmap.c: add test for bitmap_cut()
Inspired by an original patch from Yury Norov: introduce a test for
bitmap_cut() that also makes sure functionality is as described for
partially overlapping src and dst.
Stefano Brivio [Wed, 12 Aug 2020 01:34:29 +0000 (18:34 -0700)]
lib/bitmap.c: fix bitmap_cut() for partial overlapping case
Patch series "lib: Fix bitmap_cut() for overlaps, add test"
This patch (of 2):
Yury Norov reports that bitmap_cut() will not produce the right outcome if
src and dst partially overlap, with src pointing at some location after
dst, because the memmove() affects src before we store the bits that we
need to keep, that is, the bits preceding the cut -- as long as we the
beginning of the cut is not aligned to a long.
Fix this by storing those bits before the memmove().
Note that this is just a theoretical concern so far, as the only user of
this function, pipapo_drop() from the nftables set back-end implemented in
net/netfilter/nft_set_pipapo.c, always supplies entirely overlapping src
and dst.
Feng Tang [Wed, 12 Aug 2020 01:34:13 +0000 (18:34 -0700)]
./Makefile: add debug option to enable function aligned on 32 bytes
Recently 0day reported many strange performance changes (regression or
improvement), in which there was no obvious relation between the culprit
commit and the benchmark at the first look, and it causes people to doubt
the test itself is wrong.
Upon further check, many of these cases are caused by the change to the
alignment of kernel text or data, as whole text/data of kernel are linked
together, change in one domain may affect alignments of other domains.
gcc has an option '-falign-functions=n' to force text aligned, and with
that option enabled, some of those performance changes will be gone, like
[1][2][3].
Add this option so that developers and 0day can easily find performance
bump caused by text alignment change, as tracking these strange bump is
quite time consuming. Though it can't help in other cases like data
alignment changes like [4].
Following is some size data for v5.7 kernel built with a RHEL config used
in 0day:
Add a helper that waits for a pid and stores the status in the passed in
kernel pointer. Use it to fix the usage of kernel_wait4 in
call_usermodehelper_exec_sync that only happens to work due to the
implicit set_fs(KERNEL_DS) for kernel threads.
alpha: fix annotation of io{read,write}{16,32}be()
These accessors must be used to read/write a big-endian bus. The value
returned or written is native-endian.
However, these accessors are defined using be{16,32}_to_cpu() or
cpu_to_be{16,32}() to make the endian conversion but these expect a
__be{16,32} when none is present. Keeping them would need a force cast
that would solve nothing at all.
So, do the conversion using swab{16,32}, like done in asm-generic for
similar situations.
exec: use force_uaccess_begin during exec and exit
Both exec and exit want to ensure that the uaccess routines actually do
access user pointers. Use the newly added force_uaccess_begin helper
instead of an open coded set_fs for that to prepare for kernel builds
where set_fs() does not exist.
Add helpers to wrap the get_fs/set_fs magic for undoing any damange done
by set_fs(KERNEL_DS). There is no real functional benefit, but this
documents the intent of these calls better, and will allow stubbing the
functions out easily for kernels builds that do not allow address space
overrides in the future.
syscalls: use uaccess_kernel in addr_limit_user_check
Patch series "clean up address limit helpers", v2.
In preparation for eventually phasing out direct use of set_fs(), this
series removes the segment_eq() arch helper that is only used to implement
or duplicate the uaccess_kernel() API, and then adds descriptive helpers
to force the kernel address limit.
This patch (of 6):
Use the uaccess_kernel helper instead of duplicating it.
mm, memory_hotplug: update pcp lists everytime onlining a memory block
When onlining a first memory block in a zone, pcp lists are not updated
thus pcp struct will have the default setting of ->high = 0,->batch = 1.
This means till the second memory block in a zone(if it have) is onlined
the pcp lists of this zone will not contain any pages because pcp's
->count is always greater than ->high thus free_pcppages_bulk() is called
to free batch size(=1) pages every time system wants to add a page to the
pcp list through free_unref_page().
To put this in a word, system is not using benefits offered by the pcp
lists when there is a single onlineable memory block in a zone. Correct
this by always updating the pcp lists when memory block is onlined.
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