Commit a7f4e6e4 authored by Zach O'Keefe's avatar Zach O'Keefe Committed by Andrew Morton
Browse files

mm/thp: add flag to enforce sysfs THP in hugepage_vma_check() 

MADV_COLLAPSE is not coupled to the kernel-oriented sysfs THP settings[1].

hugepage_vma_check() is the authority on determining if a VMA is eligible
for THP allocation/collapse, and currently enforces the sysfs THP
settings.  Add a flag to disable these checks.  For now, only apply this
arg to anon and file, which use /sys/kernel/transparent_hugepage/enabled. 
We can expand this to shmem, which uses
/sys/kernel/transparent_hugepage/shmem_enabled, later.

Use this flag in collapse_pte_mapped_thp() where previously the VMA flags
passed to hugepage_vma_check() were OR'd with VM_HUGEPAGE to elide the
VM_HUGEPAGE check in "madvise" THP mode.  Prior to "mm: khugepaged: check
THP flag in hugepage_vma_check()", this check also didn't check "never"
THP mode.  As such, this restores the previous behavior of
collapse_pte_mapped_thp() where sysfs THP settings are ignored.  See
comment in code for justification why this is OK.

[1] https://lore.kernel.org/linux-mm/CAAa6QmQxay1_=Pmt8oCX2-Va18t44FV-Vs-WsQt_6+qBks4nZA@mail.gmail.com/

Link: https://lkml.kernel.org/r/20220706235936.2197195-8-zokeefe@google.com


Signed-off-by: default avatarZach O'Keefe <zokeefe@google.com>
Reviewed-by: default avatarYang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Pavel Begunkov <asml.silence@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent d8ea7cc8

fs/proc/task_mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -864,7 +864,7 @@ static int show_smap(struct seq_file *m, void *v) 
	__show_smap(m, &mss, false);



	seq_printf(m, "THPeligible:    %d\n",

		   hugepage_vma_check(vma, vma->vm_flags, true, false));

		   hugepage_vma_check(vma, vma->vm_flags, true, false, true));



	if (arch_pkeys_enabled())

		seq_printf(m, "ProtectionKey:  %8u\n", vma_pkey(vma));

include/linux/huge_mm.h

+4 −5
Original line number Diff line number Diff line
@@ -168,9 +168,8 @@ static inline bool file_thp_enabled(struct vm_area_struct *vma) 
	       !inode_is_open_for_write(inode) && S_ISREG(inode->i_mode);

}



bool hugepage_vma_check(struct vm_area_struct *vma,

			unsigned long vm_flags,

			bool smaps, bool in_pf);

bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,

			bool smaps, bool in_pf, bool enforce_sysfs);



#define transparent_hugepage_use_zero_page()				\

	(transparent_hugepage_flags &					\
@@ -321,8 +320,8 @@ static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, 
}



static inline bool hugepage_vma_check(struct vm_area_struct *vma,

				       unsigned long vm_flags,

				       bool smaps, bool in_pf)

				      unsigned long vm_flags, bool smaps,

				      bool in_pf, bool enforce_sysfs)

{

	return false;

}

mm/huge_memory.c

+6 −8
Original line number Diff line number Diff line
@@ -70,9 +70,8 @@ static atomic_t huge_zero_refcount; 
struct page *huge_zero_page __read_mostly;

unsigned long huge_zero_pfn __read_mostly = ~0UL;



bool hugepage_vma_check(struct vm_area_struct *vma,

			unsigned long vm_flags,

			bool smaps, bool in_pf)

bool hugepage_vma_check(struct vm_area_struct *vma, unsigned long vm_flags,

			bool smaps, bool in_pf, bool enforce_sysfs)

{

	if (!vma->vm_mm)		/* vdso */

		return false;
@@ -121,11 +120,10 @@ bool hugepage_vma_check(struct vm_area_struct *vma, 
	if (!in_pf && shmem_file(vma->vm_file))

		return shmem_huge_enabled(vma);



	if (!hugepage_flags_enabled())

		return false;



	/* THP settings require madvise. */

	if (!(vm_flags & VM_HUGEPAGE) && !hugepage_flags_always())

	/* Enforce sysfs THP requirements as necessary */

	if (enforce_sysfs &&

	    (!hugepage_flags_enabled() || (!(vm_flags & VM_HUGEPAGE) &&

					   !hugepage_flags_always())))

		return false;



	/* Only regular file is valid */

mm/khugepaged.c

+14 −11
Original line number Diff line number Diff line
@@ -478,7 +478,7 @@ void khugepaged_enter_vma(struct vm_area_struct *vma, 
{

	if (!test_bit(MMF_VM_HUGEPAGE, &vma->vm_mm->flags) &&

	    hugepage_flags_enabled()) {

		if (hugepage_vma_check(vma, vm_flags, false, false))

		if (hugepage_vma_check(vma, vm_flags, false, false, true))

			__khugepaged_enter(vma->vm_mm);

	}

}
@@ -848,7 +848,8 @@ static bool khugepaged_alloc_page(struct page **hpage, gfp_t gfp, int node) 
 */



static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,

		struct vm_area_struct **vmap)

				   struct vm_area_struct **vmap,

				   struct collapse_control *cc)

{

	struct vm_area_struct *vma;
@@ -861,7 +862,8 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, 


	if (!transhuge_vma_suitable(vma, address))

		return SCAN_ADDRESS_RANGE;

	if (!hugepage_vma_check(vma, vma->vm_flags, false, false))

	if (!hugepage_vma_check(vma, vma->vm_flags, false, false,

				cc->is_khugepaged))

		return SCAN_VMA_CHECK;

	/*

	 * Anon VMA expected, the address may be unmapped then
@@ -980,7 +982,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, 
		goto out_nolock;



	mmap_read_lock(mm);

	result = hugepage_vma_revalidate(mm, address, &vma);

	result = hugepage_vma_revalidate(mm, address, &vma, cc);

	if (result != SCAN_SUCCEED) {

		mmap_read_unlock(mm);

		goto out_nolock;
@@ -1012,7 +1014,7 @@ static int collapse_huge_page(struct mm_struct *mm, unsigned long address, 
	 * handled by the anon_vma lock + PG_lock.

	 */

	mmap_write_lock(mm);

	result = hugepage_vma_revalidate(mm, address, &vma);

	result = hugepage_vma_revalidate(mm, address, &vma, cc);

	if (result != SCAN_SUCCEED)

		goto out_up_write;

	/* check if the pmd is still valid */
@@ -1360,12 +1362,13 @@ void collapse_pte_mapped_thp(struct mm_struct *mm, unsigned long addr) 
		return;



	/*

	 * This vm_flags may not have VM_HUGEPAGE if the page was not

	 * collapsed by this mm. But we can still collapse if the page is

	 * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check()

	 * will not fail the vma for missing VM_HUGEPAGE

	 * If we are here, we've succeeded in replacing all the native pages

	 * in the page cache with a single hugepage. If a mm were to fault-in

	 * this memory (mapped by a suitably aligned VMA), we'd get the hugepage

	 * and map it by a PMD, regardless of sysfs THP settings. As such, let's

	 * analogously elide sysfs THP settings here.

	 */

	if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false, false))

	if (!hugepage_vma_check(vma, vma->vm_flags, false, false, false))

		return;



	/* Keep pmd pgtable for uffd-wp; see comment in retract_page_tables() */
@@ -2048,7 +2051,7 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, int *result, 
			progress++;

			break;

		}

		if (!hugepage_vma_check(vma, vma->vm_flags, false, false)) {

		if (!hugepage_vma_check(vma, vma->vm_flags, false, false, true)) {

skip:

			progress++;

			continue;

mm/memory.c

+2 −2
Original line number Diff line number Diff line
@@ -4985,7 +4985,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, 
		return VM_FAULT_OOM;

retry_pud:

	if (pud_none(*vmf.pud) &&

	    hugepage_vma_check(vma, vm_flags, false, true)) {

	    hugepage_vma_check(vma, vm_flags, false, true, true)) {

		ret = create_huge_pud(&vmf);

		if (!(ret & VM_FAULT_FALLBACK))

			return ret;
@@ -5019,7 +5019,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, 
		goto retry_pud;



	if (pmd_none(*vmf.pmd) &&

	    hugepage_vma_check(vma, vm_flags, false, true)) {

	    hugepage_vma_check(vma, vm_flags, false, true, true)) {

		ret = create_huge_pmd(&vmf);

		if (!(ret & VM_FAULT_FALLBACK))

			return ret;