mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 19:00:25 +00:00
s390/gmap: improve THP splitting
During s390_enable_sie(), we need to take care of splitting all qemu user process THP mappings. This is currently done with follow_page(FOLL_SPLIT), by simply iterating over all vma ranges, with PAGE_SIZE increment. This logic is sub-optimal and can result in a lot of unnecessary overhead, especially when using qemu and ASAN with large shadow map. Ilya reported significant system slow-down with one CPU busy for a long time and overall unresponsiveness. Fix this by using walk_page_vma() and directly calling split_huge_pmd() only for present pmds, which greatly reduces overhead. Cc: <stable@vger.kernel.org> # v5.4+ Reported-by: Ilya Leoshkevich <iii@linux.ibm.com> Tested-by: Ilya Leoshkevich <iii@linux.ibm.com> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
parent
f0cbd3b83e
commit
ba925fa350
1 changed files with 20 additions and 7 deletions
|
@ -2485,23 +2485,36 @@ void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long bitmap[4],
|
|||
}
|
||||
EXPORT_SYMBOL_GPL(gmap_sync_dirty_log_pmd);
|
||||
|
||||
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
||||
static int thp_split_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
|
||||
unsigned long end, struct mm_walk *walk)
|
||||
{
|
||||
struct vm_area_struct *vma = walk->vma;
|
||||
|
||||
split_huge_pmd(vma, pmd, addr);
|
||||
return 0;
|
||||
}
|
||||
|
||||
static const struct mm_walk_ops thp_split_walk_ops = {
|
||||
.pmd_entry = thp_split_walk_pmd_entry,
|
||||
};
|
||||
|
||||
static inline void thp_split_mm(struct mm_struct *mm)
|
||||
{
|
||||
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
||||
struct vm_area_struct *vma;
|
||||
unsigned long addr;
|
||||
|
||||
for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
|
||||
for (addr = vma->vm_start;
|
||||
addr < vma->vm_end;
|
||||
addr += PAGE_SIZE)
|
||||
follow_page(vma, addr, FOLL_SPLIT);
|
||||
vma->vm_flags &= ~VM_HUGEPAGE;
|
||||
vma->vm_flags |= VM_NOHUGEPAGE;
|
||||
walk_page_vma(vma, &thp_split_walk_ops, NULL);
|
||||
}
|
||||
mm->def_flags |= VM_NOHUGEPAGE;
|
||||
#endif
|
||||
}
|
||||
#else
|
||||
static inline void thp_split_mm(struct mm_struct *mm)
|
||||
{
|
||||
}
|
||||
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
|
||||
|
||||
/*
|
||||
* Remove all empty zero pages from the mapping for lazy refaulting
|
||||
|
|
Loading…
Reference in a new issue