| Message ID | 20220131192308.608837-5-longman@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/page_owner: Extend page_owner to show memcg information | expand |
On Mon, Jan 31, 2022 at 02:23:08PM -0500, Waiman Long wrote: > The page_owner information currently includes the pid of the calling > task. That is useful as long as the task is still running. Otherwise, > the number is meaningless. To have more information about the allocating > tasks that had exited by the time the page_owner information is > retrieved, we need to store the command name of the task. > > Add a new comm field into page_owner structure to store the command name > and display it when the page_owner information is retrieved. Only the > first 15 characters of the command name will be copied, but that should > be enough in most cases. Even for those commands with longer names, > it shouldn't be hard to guess what they are. > > Signed-off-by: Waiman Long <longman@redhat.com> > --- > mm/page_owner.c | 16 ++++++++++++---- > 1 file changed, 12 insertions(+), 4 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index a471c74c7fe0..8b2b381fd986 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -20,6 +20,7 @@ > * to use off stack temporal storage > */ > #define PAGE_OWNER_STACK_DEPTH (16) > +#define PAGE_OWNER_COMM_LEN 16 Not sure I understand why not simply use TASK_COMM_LEN ?
On 1/31/22 15:54, Roman Gushchin wrote: > On Mon, Jan 31, 2022 at 02:23:08PM -0500, Waiman Long wrote: >> The page_owner information currently includes the pid of the calling >> task. That is useful as long as the task is still running. Otherwise, >> the number is meaningless. To have more information about the allocating >> tasks that had exited by the time the page_owner information is >> retrieved, we need to store the command name of the task. >> >> Add a new comm field into page_owner structure to store the command name >> and display it when the page_owner information is retrieved. Only the >> first 15 characters of the command name will be copied, but that should >> be enough in most cases. Even for those commands with longer names, >> it shouldn't be hard to guess what they are. >> >> Signed-off-by: Waiman Long <longman@redhat.com> >> --- >> mm/page_owner.c | 16 ++++++++++++---- >> 1 file changed, 12 insertions(+), 4 deletions(-) >> >> diff --git a/mm/page_owner.c b/mm/page_owner.c >> index a471c74c7fe0..8b2b381fd986 100644 >> --- a/mm/page_owner.c >> +++ b/mm/page_owner.c >> @@ -20,6 +20,7 @@ >> * to use off stack temporal storage >> */ >> #define PAGE_OWNER_STACK_DEPTH (16) >> +#define PAGE_OWNER_COMM_LEN 16 > Not sure I understand why not simply use TASK_COMM_LEN ? Yes, you are right. I thought TASK_COMM_LEN is larger than 16 without actually checking it. Will fix that. Cheers, Longman
diff --git a/mm/page_owner.c b/mm/page_owner.c index a471c74c7fe0..8b2b381fd986 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -20,6 +20,7 @@ * to use off stack temporal storage */ #define PAGE_OWNER_STACK_DEPTH (16) +#define PAGE_OWNER_COMM_LEN 16 struct page_owner { unsigned short order; @@ -29,6 +30,7 @@ struct page_owner { depot_stack_handle_t free_handle; u64 ts_nsec; u64 free_ts_nsec; + char comm[PAGE_OWNER_COMM_LEN]; pid_t pid; }; @@ -146,6 +148,7 @@ void __reset_page_owner(struct page *page, unsigned short order) page_owner = get_page_owner(page_ext); page_owner->free_handle = handle; page_owner->free_ts_nsec = free_ts_nsec; + page_owner->comm[0] = '\0'; page_ext = page_ext_next(page_ext); } } @@ -165,6 +168,8 @@ static inline void __set_page_owner_handle(struct page_ext *page_ext, page_owner->last_migrate_reason = -1; page_owner->pid = current->pid; page_owner->ts_nsec = local_clock(); + strlcpy(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); @@ -232,6 +237,7 @@ void __folio_copy_owner(struct folio *newfolio, struct folio *old) new_page_owner->pid = old_page_owner->pid; 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); /* * We don't clear the bit on the old folio as it's going to be freed @@ -376,10 +382,11 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn, return -ENOMEM; ret = scnprintf(kbuf, count, - "Page allocated via order %u, mask %#x(%pGg), pid %d, ts %llu ns, free_ts %llu ns\n", + "Page allocated via order %u, mask %#x(%pGg), pid %d (%s), ts %llu ns, free_ts %llu ns\n", page_owner->order, page_owner->gfp_mask, &page_owner->gfp_mask, page_owner->pid, - page_owner->ts_nsec, page_owner->free_ts_nsec); + page_owner->comm, page_owner->ts_nsec, + page_owner->free_ts_nsec); /* Print information relevant to grouping pages by mobility */ pageblock_mt = get_pageblock_migratetype(page); @@ -446,9 +453,10 @@ void __dump_page_owner(const struct page *page) else pr_alert("page_owner tracks the page as freed\n"); - pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d, ts %llu, free_ts %llu\n", + pr_alert("page last allocated via order %u, migratetype %s, gfp_mask %#x(%pGg), pid %d (%s), ts %llu, free_ts %llu\n", page_owner->order, migratetype_names[mt], gfp_mask, &gfp_mask, - page_owner->pid, page_owner->ts_nsec, page_owner->free_ts_nsec); + page_owner->pid, page_owner->comm, page_owner->ts_nsec, + page_owner->free_ts_nsec); handle = READ_ONCE(page_owner->handle); if (!handle)
The page_owner information currently includes the pid of the calling task. That is useful as long as the task is still running. Otherwise, the number is meaningless. To have more information about the allocating tasks that had exited by the time the page_owner information is retrieved, we need to store the command name of the task. Add a new comm field into page_owner structure to store the command name and display it when the page_owner information is retrieved. Only the first 15 characters of the command name will be copied, but that should be enough in most cases. Even for those commands with longer names, it shouldn't be hard to guess what they are. Signed-off-by: Waiman Long <longman@redhat.com> --- mm/page_owner.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)