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hugetlbfs: clean up command line processing 

With all hugetlb page processing done in a single file clean up code.

- Make code match desired semantics
  - Update documentation with semantics
- Make all warnings and errors messages start with 'HugeTLB:'.
- Consistently name command line parsing routines.
- Warn if !hugepages_supported() and command line parameters have
  been specified.
- Add comments to code
  - Describe some of the subtle interactions
  - Describe semantics of command line arguments

This patch also fixes issues with implicitly setting the number of
gigantic huge pages to preallocate.  Previously on X86 command line,

        hugepages=2 default_hugepagesz=1G

would result in zero 1G pages being preallocated and,

        # grep HugePages_Total /proc/meminfo
        HugePages_Total:       0
        # sysctl -a | grep nr_hugepages
        vm.nr_hugepages = 2
        vm.nr_hugepages_mempolicy = 2
        # cat /proc/sys/vm/nr_hugepages
        2

After this patch 2 gigantic pages will be preallocated and all the proc,
sysfs, sysctl and meminfo files will accurately reflect this.

To address the issue with gigantic pages, a small change in behavior was
made to command line processing.  Previously the command line,

        hugepages=128 default_hugepagesz=2M hugepagesz=2M hugepages=256

would result in the allocation of 256 2M huge pages.  The value 128 would
be ignored without any warning.  After this patch, 128 2M pages will be
allocated and a warning message will be displayed indicating the value of
256 is ignored.  This change in behavior is required because allocation of
implicitly specified gigantic pages must be done when the
default_hugepagesz= is encountered for gigantic pages.  Previously the
code waited until later in the boot process (hugetlb_init), to allocate
pages of default size.  However the bootmem allocator required for
gigantic allocations is not available at this time.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Sandipan Das <sandipan@linux.ibm.com>
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>	[s390]
Acked-by: Will Deacon <will@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Longpeng <longpeng2@huawei.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Nitesh Narayan Lal <nitesh@redhat.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Link: http://lkml.kernel.org/r/20200417185049.275845-5-mike.kravetz@oracle.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mike Kravetz 2020-06-03 16:00:46 -07:00 committed by Linus Torvalds
parent 3823783088
commit 282f421438
3 changed files with 195 additions and 49 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

40
Documentation/admin-guide/kernel-parameters.txt
View File

@ -834,12 +834,15 @@
See also Documentation/networking/decnet.txt.
default_hugepagesz=
[same as hugepagesz=] The size of the default
HugeTLB page size. This is the size represented by
the legacy /proc/ hugepages APIs, used for SHM, and
default size when mounting hugetlbfs filesystems.
Defaults to the default architecture's huge page size
if not specified.
[HW] The size of the default HugeTLB page. This is
the size represented by the legacy /proc/ hugepages
APIs. In addition, this is the default hugetlb size
used for shmget(), mmap() and mounting hugetlbfs
filesystems. If not specified, defaults to the
architecture's default huge page size. Huge page
sizes are architecture dependent. See also
Documentation/admin-guide/mm/hugetlbpage.rst.
Format: size[KMG]
deferred_probe_timeout=
[KNL] Debugging option to set a timeout in seconds for
@ -1479,13 +1482,24 @@
hugepages using the cma allocator. If enabled, the
boot-time allocation of gigantic hugepages is skipped.
hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
On x86-64 and powerpc, this option can be specified
multiple times interleaved with hugepages= to reserve
huge pages of different sizes. Valid pages sizes on
x86-64 are 2M (when the CPU supports "pse") and 1G
(when the CPU supports the "pdpe1gb" cpuinfo flag).
hugepages= [HW] Number of HugeTLB pages to allocate at boot.
If this follows hugepagesz (below), it specifies
the number of pages of hugepagesz to be allocated.
If this is the first HugeTLB parameter on the command
line, it specifies the number of pages to allocate for
the default huge page size. See also
Documentation/admin-guide/mm/hugetlbpage.rst.
Format: <integer>
hugepagesz=
[HW] The size of the HugeTLB pages. This is used in
conjunction with hugepages (above) to allocate huge
pages of a specific size at boot. The pair
hugepagesz=X hugepages=Y can be specified once for
each supported huge page size. Huge page sizes are
architecture dependent. See also
Documentation/admin-guide/mm/hugetlbpage.rst.
Format: size[KMG]
hung_task_panic=
[KNL] Should the hung task detector generate panics.

35
Documentation/admin-guide/mm/hugetlbpage.rst
View File

@ -100,6 +100,41 @@ with a huge page size selection parameter "hugepagesz=<size>". <size> must
be specified in bytes with optional scale suffix [kKmMgG]. The default huge
page size may be selected with the "default_hugepagesz=<size>" boot parameter.
Hugetlb boot command line parameter semantics
hugepagesz - Specify a huge page size. Used in conjunction with hugepages
parameter to preallocate a number of huge pages of the specified
size. Hence, hugepagesz and hugepages are typically specified in
pairs such as:
hugepagesz=2M hugepages=512
hugepagesz can only be specified once on the command line for a
specific huge page size. Valid huge page sizes are architecture
dependent.
hugepages - Specify the number of huge pages to preallocate. This typically
follows a valid hugepagesz or default_hugepagesz parameter. However,
if hugepages is the first or only hugetlb command line parameter it
implicitly specifies the number of huge pages of default size to
allocate. If the number of huge pages of default size is implicitly
specified, it can not be overwritten by a hugepagesz,hugepages
parameter pair for the default size.
For example, on an architecture with 2M default huge page size:
hugepages=256 hugepagesz=2M hugepages=512
will result in 256 2M huge pages being allocated and a warning message
indicating that the hugepages=512 parameter is ignored. If a hugepages
parameter is preceded by an invalid hugepagesz parameter, it will
be ignored.
default_hugepagesz - Specify the default huge page size. This parameter can
only be specified once on the command line. default_hugepagesz can
optionally be followed by the hugepages parameter to preallocate a
specific number of huge pages of default size. The number of default
sized huge pages to preallocate can also be implicitly specified as
mentioned in the hugepages section above. Therefore, on an
architecture with 2M default huge page size:
hugepages=256
default_hugepagesz=2M hugepages=256
hugepages=256 default_hugepagesz=2M
will all result in 256 2M huge pages being allocated. Valid default
huge page size is architecture dependent.
When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages``
indicates the current number of pre-allocated huge pages of the default size.
Thus, one can use the following command to dynamically allocate/deallocate

169
mm/hugetlb.c
View File

@ -59,8 +59,8 @@ __initdata LIST_HEAD(huge_boot_pages);
/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
static unsigned long __initdata default_hstate_size;
static bool __initdata parsed_valid_hugepagesz = true;
static bool __initdata parsed_default_hugepagesz;
/*
* Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
@ -3060,7 +3060,7 @@ static void __init hugetlb_sysfs_init(void)
err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
hstate_kobjs, &hstate_attr_group);
if (err)
pr_err("Hugetlb: Unable to add hstate %s", h->name);
pr_err("HugeTLB: Unable to add hstate %s", h->name);
}
}
@ -3164,7 +3164,7 @@ static void hugetlb_register_node(struct node *node)
nhs->hstate_kobjs,
&per_node_hstate_attr_group);
if (err) {
pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
pr_err("HugeTLB: Unable to add hstate %s for node %d\n",
h->name, node->dev.id);
hugetlb_unregister_node(node);
break;
@ -3215,19 +3215,35 @@ static int __init hugetlb_init(void)
if (!hugepages_supported())
return 0;
if (!size_to_hstate(default_hstate_size)) {
if (default_hstate_size != 0) {
pr_err("HugeTLB: unsupported default_hugepagesz %lu. Reverting to %lu\n",
default_hstate_size, HPAGE_SIZE);
}
/*
* Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists. Some
* architectures depend on setup being done here.
*/
hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
if (!parsed_default_hugepagesz) {
/*
* If we did not parse a default huge page size, set
* default_hstate_idx to HPAGE_SIZE hstate. And, if the
* number of huge pages for this default size was implicitly
* specified, set that here as well.
* Note that the implicit setting will overwrite an explicit
* setting. A warning will be printed in this case.
*/
default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE));
if (default_hstate_max_huge_pages) {
if (default_hstate.max_huge_pages) {
char buf[32];
default_hstate_size = HPAGE_SIZE;
hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
}
default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
if (default_hstate_max_huge_pages) {
if (!default_hstate.max_huge_pages)
default_hstate.max_huge_pages = default_hstate_max_huge_pages;
string_get_size(huge_page_size(&default_hstate),
1, STRING_UNITS_2, buf, 32);
pr_warn("HugeTLB: Ignoring hugepages=%lu associated with %s page size\n",
default_hstate.max_huge_pages, buf);
pr_warn("HugeTLB: Using hugepages=%lu for number of default huge pages\n",
default_hstate_max_huge_pages);
}
default_hstate.max_huge_pages =
default_hstate_max_huge_pages;
}
}
hugetlb_cma_check();
@ -3287,20 +3303,34 @@ void __init hugetlb_add_hstate(unsigned int order)
parsed_hstate = h;
}
static int __init hugetlb_nrpages_setup(char *s)
/*
* hugepages command line processing
* hugepages normally follows a valid hugepagsz or default_hugepagsz
* specification. If not, ignore the hugepages value. hugepages can also
* be the first huge page command line option in which case it implicitly
* specifies the number of huge pages for the default size.
*/
static int __init hugepages_setup(char *s)
{
unsigned long *mhp;
static unsigned long *last_mhp;
if (!parsed_valid_hugepagesz) {
pr_warn("hugepages = %s preceded by "
"an unsupported hugepagesz, ignoring\n", s);
parsed_valid_hugepagesz = true;
return 1;
if (!hugepages_supported()) {
pr_warn("HugeTLB: huge pages not supported, ignoring hugepages = %s\n", s);
return 0;
}
if (!parsed_valid_hugepagesz) {
pr_warn("HugeTLB: hugepages=%s does not follow a valid hugepagesz, ignoring\n", s);
parsed_valid_hugepagesz = true;
return 0;
}
/*
* !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
* so this hugepages= parameter goes to the "default hstate".
* !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter
* yet, so this hugepages= parameter goes to the "default hstate".
* Otherwise, it goes with the previously parsed hugepagesz or
* default_hugepagesz.
*/
else if (!hugetlb_max_hstate)
mhp = &default_hstate_max_huge_pages;
@ -3308,8 +3338,8 @@ static int __init hugetlb_nrpages_setup(char *s)
mhp = &parsed_hstate->max_huge_pages;
if (mhp == last_mhp) {
pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
return 1;
pr_warn("HugeTLB: hugepages= specified twice without interleaving hugepagesz=, ignoring hugepages=%s\n", s);
return 0;
}
if (sscanf(s, "%lu", mhp) <= 0)
@ -3327,42 +3357,109 @@ static int __init hugetlb_nrpages_setup(char *s)
return 1;
}
__setup("hugepages=", hugetlb_nrpages_setup);
__setup("hugepages=", hugepages_setup);
/*
* hugepagesz command line processing
* A specific huge page size can only be specified once with hugepagesz.
* hugepagesz is followed by hugepages on the command line. The global
* variable 'parsed_valid_hugepagesz' is used to determine if prior
* hugepagesz argument was valid.
*/
static int __init hugepagesz_setup(char *s)
{
unsigned long size;
struct hstate *h;
parsed_valid_hugepagesz = false;
if (!hugepages_supported()) {
pr_warn("HugeTLB: huge pages not supported, ignoring hugepagesz = %s\n", s);
return 0;
}
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
parsed_valid_hugepagesz = false;
pr_err("HugeTLB: unsupported hugepagesz %s\n", s);
pr_err("HugeTLB: unsupported hugepagesz=%s\n", s);
return 0;
}
if (size_to_hstate(size)) {
pr_warn("HugeTLB: hugepagesz %s specified twice, ignoring\n", s);
return 0;
h = size_to_hstate(size);
if (h) {
/*
* hstate for this size already exists. This is normally
* an error, but is allowed if the existing hstate is the
* default hstate. More specifically, it is only allowed if
* the number of huge pages for the default hstate was not
* previously specified.
*/
if (!parsed_default_hugepagesz || h != &default_hstate ||
default_hstate.max_huge_pages) {
pr_warn("HugeTLB: hugepagesz=%s specified twice, ignoring\n", s);
return 0;
}
/*
* No need to call hugetlb_add_hstate() as hstate already
* exists. But, do set parsed_hstate so that a following
* hugepages= parameter will be applied to this hstate.
*/
parsed_hstate = h;
parsed_valid_hugepagesz = true;
return 1;
}
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
parsed_valid_hugepagesz = true;
return 1;
}
__setup("hugepagesz=", hugepagesz_setup);
/*
* default_hugepagesz command line input
* Only one instance of default_hugepagesz allowed on command line.
*/
static int __init default_hugepagesz_setup(char *s)
{
unsigned long size;
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
pr_err("HugeTLB: unsupported default_hugepagesz %s\n", s);
parsed_valid_hugepagesz = false;
if (!hugepages_supported()) {
pr_warn("HugeTLB: huge pages not supported, ignoring default_hugepagesz = %s\n", s);
return 0;
}
default_hstate_size = size;
if (parsed_default_hugepagesz) {
pr_err("HugeTLB: default_hugepagesz previously specified, ignoring %s\n", s);
return 0;
}
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
pr_err("HugeTLB: unsupported default_hugepagesz=%s\n", s);
return 0;
}
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
parsed_valid_hugepagesz = true;
parsed_default_hugepagesz = true;
default_hstate_idx = hstate_index(size_to_hstate(size));
/*
* The number of default huge pages (for this size) could have been
* specified as the first hugetlb parameter: hugepages=X. If so,
* then default_hstate_max_huge_pages is set. If the default huge
* page size is gigantic (>= MAX_ORDER), then the pages must be
* allocated here from bootmem allocator.
*/
if (default_hstate_max_huge_pages) {
default_hstate.max_huge_pages = default_hstate_max_huge_pages;
if (hstate_is_gigantic(&default_hstate))
hugetlb_hstate_alloc_pages(&default_hstate);
default_hstate_max_huge_pages = 0;
}
return 1;
}
__setup("default_hugepagesz=", default_hugepagesz_setup);