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Wysocki" , Pavel Machek , Len Brown Subject: Re: [PATCH v3 2/6] mm: remove swap_free() and always use swap_free_nr() In-Reply-To: (Ryan Roberts's message of "Fri, 3 May 2024 10:31:11 +0100") References: <20240503005023.174597-1-21cnbao@gmail.com> <20240503005023.174597-3-21cnbao@gmail.com> Date: Wed, 08 May 2024 15:56:33 +0800 Message-ID: <87y18kivny.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: kpqum4c6scgu886amj4qukc4gxz7ew6f X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8F67D4000C X-HE-Tag: 1715155112-411036 X-HE-Meta: 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 tPm1Jb/h HTI4kGf8Ws0Pf8jTlc9SJpUBNV9TxPG5nfpE2OTB9fPlM82h54lbNO3Z9FEtLIycl//O9fsA1bDILtmKIJJMFVcJDOW3BBa+iiTNDG9hFI+bj3zxO5/Wx2fHIB80Bzr5YSPY4XDuMu1X+efQLS6o2QkqhNED3UBG7I871jFsYtbL11ngn8ttwFKD0jMdyoZ1L5UV5WRe7N3mQHht3f2a1qoaAOqjC4Q00Q7Aoy+9xySRd4DX7oh4ZK6hDXJh/eXwoldE9lsLF8bEJBBm54MlmiXdxNLqYGAB9a6hw3awr+zeXj8oxjQBLkk+y/YBE8gZFAtMzVrgXYZUiS/YOkRNnN/DzzANyroly+Ctl5yleNY+goyZpv1BpC4jaZqDsMX4rn8ODMAVUY77tKmH4HnHpqFxH8YymW/B6tse0UdIJu7yMdV4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Ryan Roberts writes: > On 03/05/2024 01:50, Barry Song wrote: >> From: Barry Song >> >> 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" >> Signed-off-by: Barry Song >> Cc: "Rafael J. Wysocki" >> Cc: Pavel Machek >> Cc: Len Brown >> Cc: Hugh Dickins >> --- >> 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. Otherwise, LGTM. Feel free to add Reviewed-by: "Huang, Ying" in the future version. >> 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