[PATCH 8/8] mm: Remove PG_reclaim
From: Kirill A. Shutemov <hidden>
Date: 2025-01-13 09:35:25
Also in:
linux-fsdevel, lkml
Subsystem:
filesystems (vfs and infrastructure), fuse: filesystem in userspace, memory management, memory management - core, memory management - memory policy and migration, memory management - mglru (multi-gen lru), memory management - reclaim, memory management - swap, page cache, proc filesystem, the rest, tracing · Maintainers:
Alexander Viro, Christian Brauner, Miklos Szeredi, Andrew Morton, David Hildenbrand, Johannes Weiner, Chris Li, Kairui Song, Matthew Wilcox, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
Nobody sets the flag anymore. Remove the PG_reclaim, making PG_readhead exclusive user of the page flag bit. Signed-off-by: Kirill A. Shutemov <redacted> --- fs/fuse/dev.c | 2 +- fs/proc/page.c | 2 +- include/linux/mm_inline.h | 1 - include/linux/page-flags.h | 15 +++++---------- include/trace/events/mmflags.h | 2 +- include/uapi/linux/kernel-page-flags.h | 2 +- mm/filemap.c | 12 ------------ mm/migrate.c | 10 ++-------- mm/page-writeback.c | 16 +--------------- mm/page_io.c | 15 +++++---------- mm/swap.c | 16 ---------------- mm/vmscan.c | 7 ------- tools/mm/page-types.c | 8 +------- 13 files changed, 18 insertions(+), 90 deletions(-)
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 27ccae63495d..20005e2e1d28 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c@@ -827,7 +827,7 @@ static int fuse_check_folio(struct folio *folio) 1 << PG_lru | 1 << PG_active | 1 << PG_workingset | - 1 << PG_reclaim | + 1 << PG_readahead | 1 << PG_waiters | LRU_GEN_MASK | LRU_REFS_MASK))) { dump_page(&folio->page, "fuse: trying to steal weird page");
diff --git a/fs/proc/page.c b/fs/proc/page.c
index a55f5acefa97..59860ba2393c 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c@@ -189,7 +189,7 @@ u64 stable_page_flags(const struct page *page) u |= kpf_copy_bit(k, KPF_LRU, PG_lru); u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced); u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active); - u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim); + u |= kpf_copy_bit(k, KPF_READAHEAD, PG_readahead); #define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache)) if ((k & SWAPCACHE) == SWAPCACHE)
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index f353d3c610ac..269acf1f77b4 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h@@ -270,7 +270,6 @@ static inline bool lru_gen_add_folio(struct lruvec *lruvec, struct folio *folio, set_mask_bits(&folio->flags, LRU_GEN_MASK | BIT(PG_active), flags); lru_gen_update_size(lruvec, folio, -1, gen); - /* for folio_rotate_reclaimable() */ if (reclaiming) list_add_tail(&folio->lru, &lrugen->folios[gen][type][zone]); else
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 2414e7921eea..8f59fd8b86c9 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h@@ -63,8 +63,8 @@ * might lose their PG_swapbacked flag when they simply can be dropped (e.g. as * a result of MADV_FREE). * - * PG_referenced, PG_reclaim are used for page reclaim for anonymous and - * file-backed pagecache (see mm/vmscan.c). + * PG_referenced is used for page reclaim for anonymous and file-backed + * pagecache (see mm/vmscan.c). * * PG_arch_1 is an architecture specific page state bit. The generic code * guarantees that this bit is cleared for a page when it first is entered into
@@ -107,7 +107,7 @@ enum pageflags { PG_reserved, PG_private, /* If pagecache, has fs-private data */ PG_private_2, /* If pagecache, has fs aux data */ - PG_reclaim, /* To be reclaimed asap */ + PG_readahead, PG_swapbacked, /* Page is backed by RAM/swap */ PG_unevictable, /* Page is "unevictable" */ PG_dropbehind, /* drop pages on IO completion */
@@ -129,8 +129,6 @@ enum pageflags { #endif __NR_PAGEFLAGS, - PG_readahead = PG_reclaim, - /* Anonymous memory (and shmem) */ PG_swapcache = PG_owner_priv_1, /* Swap page: swp_entry_t in private */ /* Some filesystems */
@@ -168,7 +166,7 @@ enum pageflags { PG_xen_remapped = PG_owner_priv_1, /* non-lru isolated movable page */ - PG_isolated = PG_reclaim, + PG_isolated = PG_readahead, /* Only valid for buddy pages. Used to track pages that are reported */ PG_reported = PG_uptodate,
@@ -187,7 +185,7 @@ enum pageflags { /* At least one page in this folio has the hwpoison flag set */ PG_has_hwpoisoned = PG_active, PG_large_rmappable = PG_workingset, /* anon or file-backed */ - PG_partially_mapped = PG_reclaim, /* was identified to be partially mapped */ + PG_partially_mapped = PG_readahead, /* was identified to be partially mapped */ }; #define PAGEFLAGS_MASK ((1UL << NR_PAGEFLAGS) - 1)
@@ -594,9 +592,6 @@ TESTPAGEFLAG(Writeback, writeback, PF_NO_TAIL) TESTSCFLAG(Writeback, writeback, PF_NO_TAIL) FOLIO_FLAG(mappedtodisk, FOLIO_HEAD_PAGE) -/* PG_readahead is only used for reads; PG_reclaim is only for writes */ -PAGEFLAG(Reclaim, reclaim, PF_NO_TAIL) - TESTCLEARFLAG(Reclaim, reclaim, PF_NO_TAIL) FOLIO_FLAG(readahead, FOLIO_HEAD_PAGE) FOLIO_TEST_CLEAR_FLAG(readahead, FOLIO_HEAD_PAGE)
diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h
index 3bc8656c8359..15d92784a745 100644
--- a/include/trace/events/mmflags.h
+++ b/include/trace/events/mmflags.h@@ -114,7 +114,7 @@ DEF_PAGEFLAG_NAME(private_2), \ DEF_PAGEFLAG_NAME(writeback), \ DEF_PAGEFLAG_NAME(head), \ - DEF_PAGEFLAG_NAME(reclaim), \ + DEF_PAGEFLAG_NAME(readahead), \ DEF_PAGEFLAG_NAME(swapbacked), \ DEF_PAGEFLAG_NAME(unevictable), \ DEF_PAGEFLAG_NAME(dropbehind) \
diff --git a/include/uapi/linux/kernel-page-flags.h b/include/uapi/linux/kernel-page-flags.h
index ff8032227876..e5a9a113e079 100644
--- a/include/uapi/linux/kernel-page-flags.h
+++ b/include/uapi/linux/kernel-page-flags.h@@ -15,7 +15,7 @@ #define KPF_ACTIVE 6 #define KPF_SLAB 7 #define KPF_WRITEBACK 8 -#define KPF_RECLAIM 9 +#define KPF_READAHEAD 9 #define KPF_BUDDY 10 /* 11-20: new additions in 2.6.31 */
diff --git a/mm/filemap.c b/mm/filemap.c
index 5ca26f5e7238..8951c37c8a38 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c@@ -1624,18 +1624,6 @@ void folio_end_writeback(struct folio *folio) VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio); - /* - * folio_test_clear_reclaim() could be used here but it is an - * atomic operation and overkill in this particular case. Failing - * to shuffle a folio marked for immediate reclaim is too mild - * a gain to justify taking an atomic operation penalty at the - * end of every folio writeback. - */ - if (folio_test_reclaim(folio)) { - folio_clear_reclaim(folio); - folio_rotate_reclaimable(folio); - } - /* * Writeback does not hold a folio reference of its own, relying * on truncation to wait for the clearing of PG_writeback.
diff --git a/mm/migrate.c b/mm/migrate.c
index caadbe393aa2..beba72da5e33 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c@@ -686,6 +686,8 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) folio_set_young(newfolio); if (folio_test_idle(folio)) folio_set_idle(newfolio); + if (folio_test_readahead(folio)) + folio_set_readahead(newfolio); folio_migrate_refs(newfolio, folio); /*
@@ -728,14 +730,6 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio) if (folio_test_writeback(newfolio)) folio_end_writeback(newfolio); - /* - * PG_readahead shares the same bit with PG_reclaim. The above - * end_page_writeback() may clear PG_readahead mistakenly, so set the - * bit after that. - */ - if (folio_test_readahead(folio)) - folio_set_readahead(newfolio); - folio_copy_owner(newfolio, folio); pgalloc_tag_swap(newfolio, folio);
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 4f5970723cf2..f2b94a2cbfcf 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c@@ -2888,22 +2888,8 @@ bool folio_mark_dirty(struct folio *folio) { struct address_space *mapping = folio_mapping(folio); - if (likely(mapping)) { - /* - * readahead/folio_deactivate could remain - * PG_readahead/PG_reclaim due to race with folio_end_writeback - * About readahead, if the folio is written, the flags would be - * reset. So no problem. - * About folio_deactivate, if the folio is redirtied, - * the flag will be reset. So no problem. but if the - * folio is used by readahead it will confuse readahead - * and make it restart the size rampup process. But it's - * a trivial problem. - */ - if (folio_test_reclaim(folio)) - folio_clear_reclaim(folio); + if (likely(mapping)) return mapping->a_ops->dirty_folio(mapping, folio); - } return noop_dirty_folio(mapping, folio); }
diff --git a/mm/page_io.c b/mm/page_io.c
index 9b983de351f9..0cb71f318fb1 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c@@ -37,14 +37,11 @@ static void __end_swap_bio_write(struct bio *bio) * Re-dirty the page in order to avoid it being reclaimed. * Also print a dire warning that things will go BAD (tm) * very quickly. - * - * Also clear PG_reclaim to avoid folio_rotate_reclaimable() */ folio_mark_dirty(folio); pr_alert_ratelimited("Write-error on swap-device (%u:%u:%llu)\n", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)), (unsigned long long)bio->bi_iter.bi_sector); - folio_clear_reclaim(folio); } folio_end_writeback(folio); }
@@ -350,19 +347,17 @@ static void sio_write_complete(struct kiocb *iocb, long ret) if (ret != sio->len) { /* - * In the case of swap-over-nfs, this can be a - * temporary failure if the system has limited - * memory for allocating transmit buffers. - * Mark the page dirty and avoid - * folio_rotate_reclaimable but rate-limit the - * messages. + * In the case of swap-over-nfs, this can be a temporary failure + * if the system has limited memory for allocating transmit + * buffers. + * + * Mark the page dirty but rate-limit the messages. */ pr_err_ratelimited("Write error %ld on dio swapfile (%llu)\n", ret, swap_dev_pos(page_swap_entry(page))); for (p = 0; p < sio->pages; p++) { page = sio->bvec[p].bv_page; set_page_dirty(page); - ClearPageReclaim(page); } }
diff --git a/mm/swap.c b/mm/swap.c
index 4eb33b4804a8..5b94f13821e3 100644
--- a/mm/swap.c
+++ b/mm/swap.c@@ -221,22 +221,6 @@ static void lru_move_tail(struct lruvec *lruvec, struct folio *folio) __count_vm_events(PGROTATED, folio_nr_pages(folio)); } -/* - * Writeback is about to end against a folio which has been marked for - * immediate reclaim. If it still appears to be reclaimable, move it - * to the tail of the inactive list. - * - * folio_rotate_reclaimable() must disable IRQs, to prevent nasty races. - */ -void folio_rotate_reclaimable(struct folio *folio) -{ - if (folio_test_locked(folio) || folio_test_dirty(folio) || - folio_test_unevictable(folio)) - return; - - folio_batch_add_and_move(folio, lru_move_tail, true); -} - void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_io, unsigned int nr_rotated) {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index bb5ec22f97b5..e61e88e63511 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -3216,9 +3216,6 @@ static int folio_inc_gen(struct lruvec *lruvec, struct folio *folio, bool reclai new_flags = old_flags & ~(LRU_GEN_MASK | LRU_REFS_FLAGS); new_flags |= (new_gen + 1UL) << LRU_GEN_PGOFF; - /* for folio_end_writeback() */ - if (reclaiming) - new_flags |= BIT(PG_reclaim); } while (!try_cmpxchg(&folio->flags, &old_flags, new_flags)); lru_gen_update_size(lruvec, folio, old_gen, new_gen);
@@ -4460,9 +4457,6 @@ static bool isolate_folio(struct lruvec *lruvec, struct folio *folio, struct sca if (!folio_test_referenced(folio)) set_mask_bits(&folio->flags, LRU_REFS_MASK, 0); - /* for shrink_folio_list() */ - folio_clear_reclaim(folio); - success = lru_gen_del_folio(lruvec, folio, true); VM_WARN_ON_ONCE_FOLIO(!success, folio);
@@ -4659,7 +4653,6 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap continue; } - /* retry folios that may have missed folio_rotate_reclaimable() */ if (!skip_retry && !folio_test_active(folio) && !folio_mapped(folio) && !folio_test_dirty(folio) && !folio_test_writeback(folio)) { list_move(&folio->lru, &clean);
diff --git a/tools/mm/page-types.c b/tools/mm/page-types.c
index bcac7ebfb51f..c06647501370 100644
--- a/tools/mm/page-types.c
+++ b/tools/mm/page-types.c@@ -85,7 +85,6 @@ * not part of kernel API */ #define KPF_ANON_EXCLUSIVE 47 -#define KPF_READAHEAD 48 #define KPF_SLUB_FROZEN 50 #define KPF_SLUB_DEBUG 51 #define KPF_FILE 61
@@ -108,7 +107,7 @@ static const char * const page_flag_names[] = { [KPF_ACTIVE] = "A:active", [KPF_SLAB] = "S:slab", [KPF_WRITEBACK] = "W:writeback", - [KPF_RECLAIM] = "I:reclaim", + [KPF_READAHEAD] = "I:readahead", [KPF_BUDDY] = "B:buddy", [KPF_MMAP] = "M:mmap",
@@ -139,7 +138,6 @@ static const char * const page_flag_names[] = { [KPF_ARCH_2] = "H:arch_2", [KPF_ANON_EXCLUSIVE] = "d:anon_exclusive", - [KPF_READAHEAD] = "I:readahead", [KPF_SLUB_FROZEN] = "A:slub_frozen", [KPF_SLUB_DEBUG] = "E:slub_debug",
@@ -484,10 +482,6 @@ static uint64_t expand_overloaded_flags(uint64_t flags, uint64_t pme) flags ^= BIT(ERROR) | BIT(SLUB_DEBUG); } - /* PG_reclaim is overloaded as PG_readahead in the read path */ - if ((flags & (BIT(RECLAIM) | BIT(WRITEBACK))) == BIT(RECLAIM)) - flags ^= BIT(RECLAIM) | BIT(READAHEAD); - if (pme & PM_SOFT_DIRTY) flags |= BIT(SOFTDIRTY); if (pme & PM_FILE)
--
2.45.2