On Wed, May 8, 2024 at 7:58 PM Huang, Ying <ying.huang@xxxxxxxxx> wrote: > > Ryan Roberts <ryan.roberts@xxxxxxx> writes: > > > On 03/05/2024 01:50, Barry Song wrote: > >> From: Barry Song <v-songbaohua@xxxxxxxx> > >> > >> To streamline maintenance efforts, we propose discontinuing the use of > >> swap_free(). Instead, we can simply invoke swap_free_nr() with nr set > >> to 1. This adjustment offers the advantage of enabling batch processing > >> within kernel/power/swap.c. Furthermore, swap_free_nr() is designed with > >> a bitmap consisting of only one long, resulting in overhead that can be > >> ignored for cases where nr equals 1. > >> > >> Suggested-by: "Huang, Ying" <ying.huang@xxxxxxxxx> > >> Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx> > >> Cc: "Rafael J. Wysocki" <rafael@xxxxxxxxxx> > >> Cc: Pavel Machek <pavel@xxxxxx> > >> Cc: Len Brown <len.brown@xxxxxxxxx> > >> Cc: Hugh Dickins <hughd@xxxxxxxxxx> > >> --- > >> include/linux/swap.h | 5 ----- > >> kernel/power/swap.c | 7 +++---- > >> mm/memory.c | 2 +- > >> mm/rmap.c | 4 ++-- > >> mm/shmem.c | 4 ++-- > >> mm/swapfile.c | 19 +++++-------------- > >> 6 files changed, 13 insertions(+), 28 deletions(-) > >> > >> diff --git a/include/linux/swap.h b/include/linux/swap.h > >> index d1d35e92d7e9..f03cb446124e 100644 > >> --- a/include/linux/swap.h > >> +++ b/include/linux/swap.h > >> @@ -482,7 +482,6 @@ extern int add_swap_count_continuation(swp_entry_t, gfp_t); > >> extern void swap_shmem_alloc(swp_entry_t); > >> extern int swap_duplicate(swp_entry_t); > >> extern int swapcache_prepare(swp_entry_t); > >> -extern void swap_free(swp_entry_t); > > > > I wonder if it would be cleaner to: > > > > #define swap_free(entry) swap_free_nr((entry), 1) > > > > To save all the churn for the callsites that just want to pass a single entry? > > I prefer this way. Although I prefer inline functions. Yes, using static inline is preferable. I've recently submitted a checkpatch/codestyle for this, which can be found at: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?h=mm-everything&id=39c58d5ed036 https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?h=mm-everything&id=8379bf0b0e1f5 Using static inline aligns with the established rule. > > Otherwise, LGTM. Feel free to add > > Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx> Thanks! > > in the future version. I believe Christoph's vote leans towards simply removing swap_free_nr and renaming it to swap_free, while adding a new parameter as follows. void swap_free(swp_entry_t entry, int nr); { } now I see Ryan and you prefer static inline swap_free() { swap_free_nr(...., 1) } Chris slightly favors discouraging the use of swap_free() without the new parameter. Removing swap_free() can address this concern. It seems that maintaining swap_free() and having it call swap_free_nr() with a default value of 1 received the most support. To align with free_swap_and_cache() and free_swap_and_cache_nr(), I'll proceed with the "static inline" approach in the new version. Please voice any objections you may have, Christoph, Chris. > > >> extern void swap_free_nr(swp_entry_t entry, int nr_pages); > >> extern void swapcache_free_entries(swp_entry_t *entries, int n); > >> extern void free_swap_and_cache_nr(swp_entry_t entry, int nr); > >> @@ -561,10 +560,6 @@ static inline int swapcache_prepare(swp_entry_t swp) > >> return 0; > >> } > >> > >> -static inline void swap_free(swp_entry_t swp) > >> -{ > >> -} > >> - > >> static inline void swap_free_nr(swp_entry_t entry, int nr_pages) > >> { > >> } > >> diff --git a/kernel/power/swap.c b/kernel/power/swap.c > >> index 5bc04bfe2db1..6befaa88a342 100644 > >> --- a/kernel/power/swap.c > >> +++ b/kernel/power/swap.c > >> @@ -181,7 +181,7 @@ sector_t alloc_swapdev_block(int swap) > >> offset = swp_offset(get_swap_page_of_type(swap)); > >> if (offset) { > >> if (swsusp_extents_insert(offset)) > >> - swap_free(swp_entry(swap, offset)); > >> + swap_free_nr(swp_entry(swap, offset), 1); > >> else > >> return swapdev_block(swap, offset); > >> } > >> @@ -200,12 +200,11 @@ void free_all_swap_pages(int swap) > >> > >> while ((node = swsusp_extents.rb_node)) { > >> struct swsusp_extent *ext; > >> - unsigned long offset; > >> > >> ext = rb_entry(node, struct swsusp_extent, node); > >> rb_erase(node, &swsusp_extents); > >> - for (offset = ext->start; offset <= ext->end; offset++) > >> - swap_free(swp_entry(swap, offset)); > >> + swap_free_nr(swp_entry(swap, ext->start), > >> + ext->end - ext->start + 1); > >> > >> kfree(ext); > >> } > >> diff --git a/mm/memory.c b/mm/memory.c > >> index eea6e4984eae..f033eb3528ba 100644 > >> --- a/mm/memory.c > >> +++ b/mm/memory.c > >> @@ -4225,7 +4225,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) > >> * We're already holding a reference on the page but haven't mapped it > >> * yet. > >> */ > >> - swap_free(entry); > >> + swap_free_nr(entry, 1); > >> if (should_try_to_free_swap(folio, vma, vmf->flags)) > >> folio_free_swap(folio); > >> > >> diff --git a/mm/rmap.c b/mm/rmap.c > >> index 087a79f1f611..39ec7742acec 100644 > >> --- a/mm/rmap.c > >> +++ b/mm/rmap.c > >> @@ -1865,7 +1865,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > >> goto walk_done_err; > >> } > >> if (arch_unmap_one(mm, vma, address, pteval) < 0) { > >> - swap_free(entry); > >> + swap_free_nr(entry, 1); > >> set_pte_at(mm, address, pvmw.pte, pteval); > >> goto walk_done_err; > >> } > >> @@ -1873,7 +1873,7 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, > >> /* See folio_try_share_anon_rmap(): clear PTE first. */ > >> if (anon_exclusive && > >> folio_try_share_anon_rmap_pte(folio, subpage)) { > >> - swap_free(entry); > >> + swap_free_nr(entry, 1); > >> set_pte_at(mm, address, pvmw.pte, pteval); > >> goto walk_done_err; > >> } > >> diff --git a/mm/shmem.c b/mm/shmem.c > >> index fa2a0ed97507..bfc8a2beb24f 100644 > >> --- a/mm/shmem.c > >> +++ b/mm/shmem.c > >> @@ -1836,7 +1836,7 @@ static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index, > >> * in shmem_evict_inode(). > >> */ > >> shmem_recalc_inode(inode, -1, -1); > >> - swap_free(swap); > >> + swap_free_nr(swap, 1); > >> } > >> > >> /* > >> @@ -1927,7 +1927,7 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index, > >> > >> delete_from_swap_cache(folio); > >> folio_mark_dirty(folio); > >> - swap_free(swap); > >> + swap_free_nr(swap, 1); > >> put_swap_device(si); > >> > >> *foliop = folio; > >> diff --git a/mm/swapfile.c b/mm/swapfile.c > >> index ec12f2b9d229..ddcd0f24b9a1 100644 > >> --- a/mm/swapfile.c > >> +++ b/mm/swapfile.c > >> @@ -1343,19 +1343,6 @@ static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) > >> swap_range_free(p, offset, 1); > >> } > >> > >> -/* > >> - * Caller has made sure that the swap device corresponding to entry > >> - * is still around or has not been recycled. > >> - */ > >> -void swap_free(swp_entry_t entry) > >> -{ > >> - struct swap_info_struct *p; > >> - > >> - p = _swap_info_get(entry); > >> - if (p) > >> - __swap_entry_free(p, entry); > >> -} > >> - > >> static void cluster_swap_free_nr(struct swap_info_struct *sis, > >> unsigned long offset, int nr_pages) > >> { > >> @@ -1385,6 +1372,10 @@ static void cluster_swap_free_nr(struct swap_info_struct *sis, > >> unlock_cluster_or_swap_info(sis, ci); > >> } > >> > >> +/* > >> + * Caller has made sure that the swap device corresponding to entry > >> + * is still around or has not been recycled. > >> + */ > >> void swap_free_nr(swp_entry_t entry, int nr_pages) > >> { > >> int nr; > >> @@ -1930,7 +1921,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > >> new_pte = pte_mkuffd_wp(new_pte); > >> setpte: > >> set_pte_at(vma->vm_mm, addr, pte, new_pte); > >> - swap_free(entry); > >> + swap_free_nr(entry, 1); > >> out: > >> if (pte) > >> pte_unmap_unlock(pte, ptl); > > -- > Best Regards, > Huang, Ying Thanks Barry
