(cc s390 folks) On Tue, Sep 15, 2026 at 07:42:15PM -0400, Tal Zussman wrote: > Use a folio for the page cache page the s390 fault handler reads the
I tiny bit of context why is this only relevant for s390 would have been nice :) > old kernel's memory into. This removes four compound_head() calls and > one of the last callers of find_or_create_page(). > > The vmcore mapping only has order-0 folios, so the logic is unchanged. > > Compile tested for s390. > > Signed-off-by: Tal Zussman <[email protected]> > --- > This is based on the kexec-next branch of the liveupdate tree. > --- > fs/proc/vmcore.c | 27 ++++++++++++++------------- > 1 file changed, 14 insertions(+), 13 deletions(-) > > diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > index 44d15436439f..2dc3803aa11d 100644 > --- a/fs/proc/vmcore.c > +++ b/fs/proc/vmcore.c > @@ -474,29 +474,30 @@ static vm_fault_t mmap_vmcore_fault(struct vm_fault > *vmf) > pgoff_t index = vmf->pgoff; > struct iov_iter iter; > struct kvec kvec; > - struct page *page; > + struct folio *folio; > loff_t offset; > int rc; > > - page = find_or_create_page(mapping, index, GFP_KERNEL); > - if (!page) > + folio = __filemap_get_folio(mapping, index, > + FGP_LOCK | FGP_ACCESSED | FGP_CREAT, GFP_KERNEL); > + if (IS_ERR(folio)) > return VM_FAULT_OOM; > - if (!PageUptodate(page)) { > - offset = (loff_t) index << PAGE_SHIFT; > - kvec.iov_base = page_address(page); > - kvec.iov_len = PAGE_SIZE; > - iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, PAGE_SIZE); > + if (!folio_test_uptodate(folio)) { > + offset = folio_pos(folio); > + kvec.iov_base = folio_address(folio); > + kvec.iov_len = folio_size(folio); > + iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, folio_size(folio)); > > rc = __read_vmcore(&iter, &offset); > if (rc < 0) { > - unlock_page(page); > - put_page(page); > + folio_unlock(folio); > + folio_put(folio); > return vmf_error(rc); > } > - SetPageUptodate(page); > + folio_mark_uptodate(folio); > } > - unlock_page(page); > - vmf->page = page; > + folio_unlock(folio); > + vmf->page = folio_file_page(folio, index); > return 0; > #else > return VM_FAULT_SIGBUS; > > --- > base-commit: 4d17a004cfd5489f88ad0a7a151dea11a533338b > change-id: 20260907-vmcore-fault-folio-4b382eeff262 > > Best regards, > -- > Tal Zussman <[email protected]> > -- Sincerely yours, Mike.
