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authorOscar Salvador <osalvador@suse.de>2024-04-04 09:06:59 +0200
committerAndrew Morton <akpm@linux-foundation.org>2024-04-17 00:39:49 +0200
commitea4b5b33bf8a4936cfb07759d926db697c43fb1e (patch)
tree4aaaffb0a754e7760678e5f3f9a043a5f878aaf5 /mm/page_owner.c
parentuserfaultfd: change src_folio after ensuring it's unpinned in UFFDIO_MOVE (diff)
downloadlinux-ea4b5b33bf8a4936cfb07759d926db697c43fb1e.tar.xz
linux-ea4b5b33bf8a4936cfb07759d926db697c43fb1e.zip
mm,page_owner: update metadata for tail pages
Patch series "page_owner: Fix refcount imbalance and print fixup", v4. This series consists of a refactoring/correctness of updating the metadata of tail pages, a couple of fixups for the refcounting part and a fixup for the stack_start() function. From this series on, instead of counting the stacks, we count the outstanding nr_base_pages each stack has, which gives us a much better memory overview. The other fixup is for the migration part. A more detailed explanation can be found in the changelog of the respective patches. This patch (of 4): __set_page_owner_handle() and __reset_page_owner() update the metadata of all pages when the page is of a higher-order, but we miss to do the same when the pages are migrated. __folio_copy_owner() only updates the metadata of the head page, meaning that the information stored in the first page and the tail pages will not match. Strictly speaking that is not a big problem because 1) we do not print tail pages and 2) upon splitting all tail pages will inherit the metadata of the head page, but it is better to have all metadata in check should there be any problem, so it can ease debugging. For that purpose, a couple of helpers are created __update_page_owner_handle() which updates the metadata on allocation, and __update_page_owner_free_handle() which does the same when the page is freed. __folio_copy_owner() will make use of both as it needs to entirely replace the page_owner metadata for the new page. Link: https://lkml.kernel.org/r/20240404070702.2744-1-osalvador@suse.de Link: https://lkml.kernel.org/r/20240404070702.2744-2-osalvador@suse.de Signed-off-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Vlastimil Babka <vbabka@suse.cz> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Alexander Potapenko <glider@google.com> Cc: Alexandre Ghiti <alexghiti@rivosinc.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Marco Elver <elver@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Alexandre Ghiti <alexghiti@rivosinc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/page_owner.c137
1 files changed, 74 insertions, 63 deletions
diff --git a/mm/page_owner.c b/mm/page_owner.c
index d17d1351ec84..52d1ced0b57f 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -228,9 +228,58 @@ static void dec_stack_record_count(depot_stack_handle_t handle)
refcount_dec(&stack_record->count);
}
-void __reset_page_owner(struct page *page, unsigned short order)
+static inline void __update_page_owner_handle(struct page_ext *page_ext,
+ depot_stack_handle_t handle,
+ unsigned short order,
+ gfp_t gfp_mask,
+ short last_migrate_reason, u64 ts_nsec,
+ pid_t pid, pid_t tgid, char *comm)
{
int i;
+ struct page_owner *page_owner;
+
+ for (i = 0; i < (1 << order); i++) {
+ page_owner = get_page_owner(page_ext);
+ page_owner->handle = handle;
+ page_owner->order = order;
+ page_owner->gfp_mask = gfp_mask;
+ page_owner->last_migrate_reason = last_migrate_reason;
+ page_owner->pid = pid;
+ page_owner->tgid = tgid;
+ page_owner->ts_nsec = ts_nsec;
+ strscpy(page_owner->comm, comm,
+ sizeof(page_owner->comm));
+ __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
+ __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
+ page_ext = page_ext_next(page_ext);
+ }
+}
+
+static inline void __update_page_owner_free_handle(struct page_ext *page_ext,
+ depot_stack_handle_t handle,
+ unsigned short order,
+ pid_t pid, pid_t tgid,
+ u64 free_ts_nsec)
+{
+ int i;
+ struct page_owner *page_owner;
+
+ for (i = 0; i < (1 << order); i++) {
+ page_owner = get_page_owner(page_ext);
+ /* Only __reset_page_owner() wants to clear the bit */
+ if (handle) {
+ __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
+ page_owner->free_handle = handle;
+ }
+ page_owner->free_ts_nsec = free_ts_nsec;
+ page_owner->free_pid = current->pid;
+ page_owner->free_tgid = current->tgid;
+ page_ext = page_ext_next(page_ext);
+ }
+}
+
+void __reset_page_owner(struct page *page, unsigned short order)
+{
struct page_ext *page_ext;
depot_stack_handle_t handle;
depot_stack_handle_t alloc_handle;
@@ -245,16 +294,10 @@ void __reset_page_owner(struct page *page, unsigned short order)
alloc_handle = page_owner->handle;
handle = save_stack(GFP_NOWAIT | __GFP_NOWARN);
- for (i = 0; i < (1 << order); i++) {
- __clear_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
- page_owner->free_handle = handle;
- page_owner->free_ts_nsec = free_ts_nsec;
- page_owner->free_pid = current->pid;
- page_owner->free_tgid = current->tgid;
- page_ext = page_ext_next(page_ext);
- page_owner = get_page_owner(page_ext);
- }
+ __update_page_owner_free_handle(page_ext, handle, order, current->pid,
+ current->tgid, free_ts_nsec);
page_ext_put(page_ext);
+
if (alloc_handle != early_handle)
/*
* early_handle is being set as a handle for all those
@@ -266,36 +309,11 @@ void __reset_page_owner(struct page *page, unsigned short order)
dec_stack_record_count(alloc_handle);
}
-static inline void __set_page_owner_handle(struct page_ext *page_ext,
- depot_stack_handle_t handle,
- unsigned short order, gfp_t gfp_mask)
-{
- struct page_owner *page_owner;
- int i;
- u64 ts_nsec = local_clock();
-
- for (i = 0; i < (1 << order); i++) {
- page_owner = get_page_owner(page_ext);
- page_owner->handle = handle;
- page_owner->order = order;
- page_owner->gfp_mask = gfp_mask;
- page_owner->last_migrate_reason = -1;
- page_owner->pid = current->pid;
- page_owner->tgid = current->tgid;
- page_owner->ts_nsec = ts_nsec;
- strscpy(page_owner->comm, current->comm,
- sizeof(page_owner->comm));
- __set_bit(PAGE_EXT_OWNER, &page_ext->flags);
- __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags);
-
- page_ext = page_ext_next(page_ext);
- }
-}
-
noinline void __set_page_owner(struct page *page, unsigned short order,
gfp_t gfp_mask)
{
struct page_ext *page_ext;
+ u64 ts_nsec = local_clock();
depot_stack_handle_t handle;
handle = save_stack(gfp_mask);
@@ -303,7 +321,9 @@ noinline void __set_page_owner(struct page *page, unsigned short order,
page_ext = page_ext_get(page);
if (unlikely(!page_ext))
return;
- __set_page_owner_handle(page_ext, handle, order, gfp_mask);
+ __update_page_owner_handle(page_ext, handle, order, gfp_mask, -1,
+ current->pid, current->tgid, ts_nsec,
+ current->comm);
page_ext_put(page_ext);
inc_stack_record_count(handle, gfp_mask);
}
@@ -342,7 +362,7 @@ void __folio_copy_owner(struct folio *newfolio, struct folio *old)
{
struct page_ext *old_ext;
struct page_ext *new_ext;
- struct page_owner *old_page_owner, *new_page_owner;
+ struct page_owner *old_page_owner;
old_ext = page_ext_get(&old->page);
if (unlikely(!old_ext))
@@ -355,31 +375,21 @@ void __folio_copy_owner(struct folio *newfolio, struct folio *old)
}
old_page_owner = get_page_owner(old_ext);
- new_page_owner = get_page_owner(new_ext);
- new_page_owner->order = old_page_owner->order;
- new_page_owner->gfp_mask = old_page_owner->gfp_mask;
- new_page_owner->last_migrate_reason =
- old_page_owner->last_migrate_reason;
- new_page_owner->handle = old_page_owner->handle;
- new_page_owner->pid = old_page_owner->pid;
- new_page_owner->tgid = old_page_owner->tgid;
- new_page_owner->free_pid = old_page_owner->free_pid;
- new_page_owner->free_tgid = old_page_owner->free_tgid;
- new_page_owner->ts_nsec = old_page_owner->ts_nsec;
- new_page_owner->free_ts_nsec = old_page_owner->ts_nsec;
- strcpy(new_page_owner->comm, old_page_owner->comm);
-
+ __update_page_owner_handle(new_ext, old_page_owner->handle,
+ old_page_owner->order, old_page_owner->gfp_mask,
+ old_page_owner->last_migrate_reason,
+ old_page_owner->ts_nsec, old_page_owner->pid,
+ old_page_owner->tgid, old_page_owner->comm);
/*
- * We don't clear the bit on the old folio as it's going to be freed
- * after migration. Until then, the info can be useful in case of
- * a bug, and the overall stats will be off a bit only temporarily.
- * Also, migrate_misplaced_transhuge_page() can still fail the
- * migration and then we want the old folio to retain the info. But
- * in that case we also don't need to explicitly clear the info from
- * the new page, which will be freed.
+ * Do not proactively clear PAGE_EXT_OWNER{_ALLOCATED} bits as the folio
+ * will be freed after migration. Keep them until then as they may be
+ * useful.
*/
- __set_bit(PAGE_EXT_OWNER, &new_ext->flags);
- __set_bit(PAGE_EXT_OWNER_ALLOCATED, &new_ext->flags);
+ __update_page_owner_free_handle(new_ext, 0, old_page_owner->order,
+ old_page_owner->free_pid,
+ old_page_owner->free_tgid,
+ old_page_owner->free_ts_nsec);
+
page_ext_put(new_ext);
page_ext_put(old_ext);
}
@@ -787,8 +797,9 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
goto ext_put_continue;
/* Found early allocated page */
- __set_page_owner_handle(page_ext, early_handle,
- 0, 0);
+ __update_page_owner_handle(page_ext, early_handle, 0, 0,
+ -1, local_clock(), current->pid,
+ current->tgid, current->comm);
count++;
ext_put_continue:
page_ext_put(page_ext);