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    SubjectRe: [PATCH 12/24] mm/swap: simplify arguments for swap_cache_get_folio
    On Sun, Nov 19, 2023 at 11:48 AM Kairui Song <ryncsn@gmail.com> wrote:
    >
    > From: Kairui Song <kasong@tencent.com>
    >
    > There are only two caller now, simplify the arguments.

    I don't think this patch is needed. It will not have a real impact on
    the resulting kernel.

    >
    > Signed-off-by: Kairui Song <kasong@tencent.com>
    > ---
    > mm/shmem.c | 2 +-
    > mm/swap.h | 2 +-
    > mm/swap_state.c | 15 +++++++--------
    > 3 files changed, 9 insertions(+), 10 deletions(-)
    >
    > diff --git a/mm/shmem.c b/mm/shmem.c
    > index 0d1ce70bce38..72239061c655 100644
    > --- a/mm/shmem.c
    > +++ b/mm/shmem.c
    > @@ -1875,7 +1875,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
    > }
    >
    > /* Look it up and read it in.. */
    > - folio = swap_cache_get_folio(swap, NULL, 0);
    > + folio = swap_cache_get_folio(swap, NULL);
    > if (!folio) {
    > /* Or update major stats only when swapin succeeds?? */
    > if (fault_type) {
    > diff --git a/mm/swap.h b/mm/swap.h
    > index ac9136eee690..e43e965f123f 100644
    > --- a/mm/swap.h
    > +++ b/mm/swap.h
    > @@ -47,7 +47,7 @@ void delete_from_swap_cache(struct folio *folio);
    > void clear_shadow_from_swap_cache(int type, unsigned long begin,
    > unsigned long end);
    > struct folio *swap_cache_get_folio(swp_entry_t entry,
    > - struct vm_area_struct *vma, unsigned long addr);
    > + struct vm_fault *vmf);
    > struct folio *filemap_get_incore_folio(struct address_space *mapping,
    > pgoff_t index);
    >
    > diff --git a/mm/swap_state.c b/mm/swap_state.c
    > index e96d63bf8a22..91461e26a8cc 100644
    > --- a/mm/swap_state.c
    > +++ b/mm/swap_state.c
    > @@ -334,8 +334,7 @@ static inline bool swap_use_vma_readahead(struct swap_info_struct *si)
    > *
    > * Caller must lock the swap device or hold a reference to keep it valid.
    > */
    > -struct folio *swap_cache_get_folio(swp_entry_t entry,
    > - struct vm_area_struct *vma, unsigned long addr)
    > +struct folio *swap_cache_get_folio(swp_entry_t entry, struct vm_fault *vmf)

    I actually prefer the original code. The vm_fault is a much heavier object.
    vma and address is really what this function needs minimally. I
    consider vma and address,
    even though two arguments are simpler than vm_fault struct.

    It is possible some other non fault patch wants to lookup the swap_cache,
    then construct a vmf just for the vma and address is kind of unnatural.

    Chris

    > {
    > struct folio *folio;
    >
    > @@ -352,22 +351,22 @@ struct folio *swap_cache_get_folio(swp_entry_t entry,
    > return folio;
    >
    > readahead = folio_test_clear_readahead(folio);
    > - if (vma && vma_ra) {
    > + if (vmf && vma_ra) {
    > unsigned long ra_val;
    > int win, hits;
    >
    > - ra_val = GET_SWAP_RA_VAL(vma);
    > + ra_val = GET_SWAP_RA_VAL(vmf->vma);
    > win = SWAP_RA_WIN(ra_val);
    > hits = SWAP_RA_HITS(ra_val);
    > if (readahead)
    > hits = min_t(int, hits + 1, SWAP_RA_HITS_MAX);
    > - atomic_long_set(&vma->swap_readahead_info,
    > - SWAP_RA_VAL(addr, win, hits));
    > + atomic_long_set(&vmf->vma->swap_readahead_info,
    > + SWAP_RA_VAL(vmf->address, win, hits));
    > }
    >
    > if (readahead) {
    > count_vm_event(SWAP_RA_HIT);
    > - if (!vma || !vma_ra)
    > + if (!vmf || !vma_ra)
    > atomic_inc(&swapin_readahead_hits);
    > }
    > } else {
    > @@ -926,7 +925,7 @@ struct page *swapin_readahead(swp_entry_t entry, gfp_t gfp_mask,
    > struct page *page;
    > pgoff_t ilx;
    >
    > - folio = swap_cache_get_folio(entry, vmf->vma, vmf->address);
    > + folio = swap_cache_get_folio(entry, vmf);
    > if (folio) {
    > page = folio_file_page(folio, swp_offset(entry));
    > cache_result = SWAP_CACHE_HIT;
    > --
    > 2.42.0
    >
    >

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