| Message ID | 20231109032521.392217-4-jeff.xie@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm, page_owner: make the owner in page owner clearer | expand |
On Thu, Nov 09, 2023 at 11:25:20AM +0800, Jeff Xie wrote: > +static int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk, > + void *data, char *kbuf, size_t count) > +{ > + int ret; > + int mapcount; > + dev_t s_dev; > + struct inode *inode; > + struct vm_area_struct *vma; > + struct mm_struct *mm; > + unsigned long virtual_start = 0x0; > + unsigned long virtual_end = 0x0; > + struct address_space *mapping = data; This is just folio->mapping. > + mapcount = folio_mapcount(folio); > + if (mapcount && tsk && tsk->mm) { > + mm = tsk->mm; > + VMA_ITERATOR(vmi, mm, 0); > + mmap_read_lock(mm); > + for_each_vma(vmi, vma) { > + if (page_mapped_in_vma(&folio->page, vma)) { > + virtual_start = vma_address(&folio->page, vma); > + virtual_end = virtual_start + folio_nr_pages(folio) * PAGE_SIZE; > + break; > + } > + } > + mmap_read_unlock(mm); > + } Why not just walk the rmap directly to find out where it's mapped in any process instead of the one which allocated it?
November 9, 2023 at 10:09 PM, "Matthew Wilcox" <willy@infradead.org> wrote: > > On Thu, Nov 09, 2023 at 11:25:20AM +0800, Jeff Xie wrote: > > > > > +static int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk, > > + void *data, char *kbuf, size_t count) > > +{ > > + int ret; > > + int mapcount; > > + dev_t s_dev; > > + struct inode *inode; > > + struct vm_area_struct *vma; > > + struct mm_struct *mm; > > + unsigned long virtual_start = 0x0; > > + unsigned long virtual_end = 0x0; > > + struct address_space *mapping = data; > > > > This is just folio->mapping. Thanks, I need to know more about struct folio ;-) > > > > > + mapcount = folio_mapcount(folio); > > + if (mapcount && tsk && tsk->mm) { > > + mm = tsk->mm; > > + VMA_ITERATOR(vmi, mm, 0); > > + mmap_read_lock(mm); > > + for_each_vma(vmi, vma) { > > + if (page_mapped_in_vma(&folio->page, vma)) { > > + virtual_start = vma_address(&folio->page, vma); > > + virtual_end = virtual_start + folio_nr_pages(folio) * PAGE_SIZE; > > + break; > > + } > > + } > > + mmap_read_unlock(mm); > > + } > > > > Why not just walk the rmap directly to find out where it's mapped in > any process instead of the one which allocated it? Since the page_owner's result only shows which PID allocated this page, we only need to obtain the address space of the corresponding process for that PID. -- Jeff Xie
On Thu, Nov 09, 2023 at 03:43:10PM +0000, jeff.xie@linux.dev wrote: > November 9, 2023 at 10:09 PM, "Matthew Wilcox" <willy@infradead.org> wrote: > > Why not just walk the rmap directly to find out where it's mapped in > > any process instead of the one which allocated it? > > Since the page_owner's result only shows which PID allocated this page, we only need to obtain the address space of the corresponding process for that PID. But that's probably uninteresting. Consider, eg, a page from libc. That's going to be mapped by hundreds or even thousands of processes. And the one which originally allocated it may well have exited by this point; files often live long past the process that first reads them.
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index bcc1ea44b4e8..900aa136c71f 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1514,4 +1514,11 @@ unsigned int i_blocks_per_page(struct inode *inode, struct page *page) { return i_blocks_per_folio(inode, page_folio(page)); } +#ifndef CONFIG_PAGE_OWNER +static inline int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk, + void *data, char *kbuf, size_t count) +{ + return 0; +} +#endif #endif /* _LINUX_PAGEMAP_H */ diff --git a/mm/filemap.c b/mm/filemap.c index 9710f43a89ac..0a346443309a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -45,6 +45,7 @@ #include <linux/migrate.h> #include <linux/pipe_fs_i.h> #include <linux/splice.h> +#include <linux/page_owner.h> #include <asm/pgalloc.h> #include <asm/tlbflush.h> #include "internal.h" @@ -838,6 +839,48 @@ void replace_page_cache_folio(struct folio *old, struct folio *new) } EXPORT_SYMBOL_GPL(replace_page_cache_folio); +#ifdef CONFIG_PAGE_OWNER +static int filemap_alloc_post_page_owner(struct folio *folio, struct task_struct *tsk, + void *data, char *kbuf, size_t count) +{ + int ret; + int mapcount; + dev_t s_dev; + struct inode *inode; + struct vm_area_struct *vma; + struct mm_struct *mm; + unsigned long virtual_start = 0x0; + unsigned long virtual_end = 0x0; + struct address_space *mapping = data; + + mapcount = folio_mapcount(folio); + if (mapcount && tsk && tsk->mm) { + mm = tsk->mm; + VMA_ITERATOR(vmi, mm, 0); + mmap_read_lock(mm); + for_each_vma(vmi, vma) { + if (page_mapped_in_vma(&folio->page, vma)) { + virtual_start = vma_address(&folio->page, vma); + virtual_end = virtual_start + folio_nr_pages(folio) * PAGE_SIZE; + break; + } + } + mmap_read_unlock(mm); + } + + inode = mapping->host; + if (mapping->host->i_sb) + s_dev = mapping->host->i_sb->s_dev; + else + s_dev = mapping->host->i_rdev; + ret = scnprintf(kbuf, count, "FILE_PAGE dev %d:%d ino:%lu index:0x%lx mapcount:%d refcount:%d 0x%lx - 0x%lx\n", + MAJOR(s_dev), MINOR(s_dev), inode->i_ino, folio->index, mapcount, folio_ref_count(folio), + virtual_start, virtual_end); + + return ret; +} +#endif + noinline int __filemap_add_folio(struct address_space *mapping, struct folio *folio, pgoff_t index, gfp_t gfp, void **shadowp) { @@ -915,6 +958,7 @@ noinline int __filemap_add_folio(struct address_space *mapping, if (xas_error(&xas)) goto error; + set_folio_alloc_post_page_owner(folio, filemap_alloc_post_page_owner, mapping); trace_mm_filemap_add_to_page_cache(folio); return 0; error:
Implement the callback function filemap_alloc_post_page_owner for the page_owner to make the owner of the file page clearer For the pid 98: [root@JeffXie ]# cat /proc/98/maps 00400000-00401000 r--p 00000000 fd:00 1954 /test/mm/a.out 00401000-00499000 r-xp 00001000 fd:00 1954 /test/mm/a.out 00499000-004c2000 r--p 00099000 fd:00 1954 /test/mm/a.out 004c2000-004c6000 r--p 000c1000 fd:00 1954 /test/mm/a.out 004c6000-004c9000 rw-p 000c5000 fd:00 1954 /test/mm/a.out 004c9000-004ce000 rw-p 00000000 00:00 0 01d97000-01db9000 rw-p 00000000 00:00 0 [heap] 7f1588fc8000-7f1588fc9000 rw-p 00000000 fd:00 1945 /a.txt 7ffda207a000-7ffda209b000 rw-p 00000000 00:00 0 [stack] 7ffda2152000-7ffda2156000 r--p 00000000 00:00 0 [vvar] 7ffda2156000-7ffda2158000 r-xp 00000000 00:00 0 [vdso] ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0 [vsyscall] added: "FILE_PAGE dev 253:0 ino:1954 index:0xc1 mapcount:1 refcount:2 0x4c2000 - 0x4c3000" Page allocated via order 0, mask 0x152c4a(GFP_NOFS|__GFP_HIGHMEM|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE),\ pid 98, tgid 98 (a.out), ts 28441476044 ns FILE_PAGE dev 253:0 ino:1954 index:0xc1 mapcount:1 refcount:2 0x4c2000 - 0x4c3000 PFN 0x5be8e type Movable Block 735 type Movable Flags 0x1fffc0000020028(uptodate|lru|mappedtodisk|node=0|zone=1|lastcpupid=0x3fff) post_alloc_hook+0x77/0xf0 get_page_from_freelist+0x58d/0x14e0 __alloc_pages+0x1b2/0x380 alloc_pages_mpol+0x97/0x1f0 folio_alloc+0x18/0x50 page_cache_ra_unbounded+0x9b/0x1a0 filemap_fault+0x5f7/0xc20 __do_fault+0x31/0xc0 __handle_mm_fault+0x1333/0x1760 handle_mm_fault+0xbc/0x2f0 do_user_addr_fault+0x1f8/0x5e0 exc_page_fault+0x73/0x170 asm_exc_page_fault+0x26/0x30 Charged to memcg / Signed-off-by: Jeff Xie <jeff.xie@linux.dev> --- include/linux/pagemap.h | 7 +++++++ mm/filemap.c | 44 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 51 insertions(+)