user/sven/linux.git/mm/debug.c, branch v5.10.42

mm, dump_page: rename head_mapcount() --> head_compound_mapcount()

2020-10-14T01:38:29Z

Rename head_pincount() --> head_compound_pincount(). These names are more accurate (or less misleading) than the original ones. Signed-off-by: John Hubbard Signed-off-by: Andrew Morton Cc: Qian Cai Cc: Matthew Wilcox Cc: Vlastimil Babka Cc: Kirill A. Shutemov Cc: Mike Rapoport Cc: William Kucharski Link: https://lkml.kernel.org/r/20200807183358.105097-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds

mm/debug.c: do not dereference i_ino blindly

2020-10-14T01:38:29Z

__dump_page() checks i_dentry is fetchable and i_ino is earlier in the struct than i_ino, so it ought to work fine, but it's possible that struct randomisation has reordered i_ino after i_dentry and the pointer is just wild enough that i_dentry is fetchable and i_ino isn't. Also print the inode number if the dentry is invalid. Reported-by: Vlastimil Babka Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Reviewed-by: John Hubbard Reviewed-by: Mike Rapoport Link: https://lkml.kernel.org/r/20200819185710.28180-1-willy@infradead.org Signed-off-by: Linus Torvalds

mm, dump_page: do not crash with bad compound_mapcount()

2020-08-07T18:33:23Z

If a compound page is being split while dump_page() is being run on that page, we can end up calling compound_mapcount() on a page that is no longer compound. This leads to a crash (already seen at least once in the field), due to the VM_BUG_ON_PAGE() assertion inside compound_mapcount(). (The above is from Matthew Wilcox's analysis of Qian Cai's bug report.) A similar problem is possible, via compound_pincount() instead of compound_mapcount(). In order to avoid this kind of crash, make dump_page() slightly more robust, by providing a pair of simpler routines that don't contain assertions: head_mapcount() and head_pincount(). For debug tools, we don't want to go *too* far in this direction, but this is a simple small fix, and the crash has already been seen, so it's a good trade-off. Reported-by: Qian Cai Suggested-by: Matthew Wilcox Signed-off-by: John Hubbard Signed-off-by: Andrew Morton Acked-by: Vlastimil Babka Cc: Kirill A. Shutemov Cc: Mike Rapoport Cc: William Kucharski Link: http://lkml.kernel.org/r/20200804214807.169256-1-jhubbard@nvidia.com Signed-off-by: Linus Torvalds

mm/debug: print hashed address of struct page

2020-08-07T18:33:23Z

The actual address of the struct page isn't particularly helpful, while the hashed address helps match with other messages elsewhere. Add the PFN that the page refers to in order to help diagnose problems where the page is improperly aligned for the purpose. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Reviewed-by: John Hubbard Acked-by: Mike Rapoport Cc: "Kirill A. Shutemov" Cc: Vlastimil Babka Cc: William Kucharski Link: http://lkml.kernel.org/r/20200709202117.7216-7-willy@infradead.org Signed-off-by: Linus Torvalds

mm/debug: print the inode number in dump_page

2020-08-07T18:33:23Z

The inode number helps correlate this page with debug messages elsewhere in the kernel. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Reviewed-by: John Hubbard Acked-by: Mike Rapoport Cc: "Kirill A. Shutemov" Cc: Vlastimil Babka Cc: William Kucharski Link: http://lkml.kernel.org/r/20200709202117.7216-6-willy@infradead.org Signed-off-by: Linus Torvalds

mm/debug: switch dump_page to get_kernel_nofault

2020-08-07T18:33:23Z

This is simpler to use than copy_from_kernel_nofault(). Also make some of the related error messages less verbose. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Acked-by: Mike Rapoport Acked-by: Vlastimil Babka Cc: John Hubbard Cc: "Kirill A. Shutemov" Cc: William Kucharski Link: http://lkml.kernel.org/r/20200709202117.7216-5-willy@infradead.org Signed-off-by: Linus Torvalds

mm/debug: print head flags in dump_page

2020-08-07T18:33:23Z

Tail page flags contain very little useful information. Print the head page's flags instead. While the flags will contain "head" for tail pages, this should not be too confusing as the previous line starts with the word "head:" and so the flags should be interpreted as belonging to the head page. Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Reviewed-by: John Hubbard Acked-by: Mike Rapoport Acked-by: Vlastimil Babka Cc: "Kirill A. Shutemov" Cc: William Kucharski Link: http://lkml.kernel.org/r/20200709202117.7216-4-willy@infradead.org Signed-off-by: Linus Torvalds

mm/debug: dump compound page information on a second line

2020-08-07T18:33:23Z

Simplify both the implementation and the output by splitting all the compound page information onto a second line. Reported-by: John Hubbard Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Tested-by: John Hubbard Reviewed-by: John Hubbard Acked-by: Mike Rapoport Acked-by: Vlastimil Babka Cc: "Kirill A. Shutemov" Cc: William Kucharski Link: http://lkml.kernel.org/r/20200709202117.7216-3-willy@infradead.org Signed-off-by: Linus Torvalds

mm/debug: handle page->mapping better in dump_page

2020-08-07T18:33:23Z

Patch series "Improvements for dump_page()", v2. Here's a sample dump of a pagecache tail page with all of the patches applied: page:000000006d1c49ca refcount:6 mapcount:0 mapping:00000000136b8d90 index:0x109 pfn:0x6c645 head:000000008bd38076 order:2 compound_mapcount:0 compound_pincount:0 aops:xfs_address_space_operations ino:800042 dentry name:"fd" flags: 0x4000000000012014(uptodate|lru|private|head) raw: 4000000000000000 ffffd46ac1b19101 ffffffff00000202 dead000000000004 raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000 head: 4000000000012014 ffffd46ac1b1bbc8 ffffd46ac1b1bc08 ffff91976f659560 head: 0000000000000108 ffff919773220680 00000006ffffffff 0000000000000000 page dumped because: testing This patch (of 6): If we can't call page_mapping() to get the page mapping, handle the anon/ksm/movable bits correctly. [akpm@linux-foundation.org: augmented code comment from John] Link: http://lkml.kernel.org/r/15cff11a-6762-8a6a-3f0e-dd227280cd6f@nvidia.com Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton Reviewed-by: John Hubbard Acked-by: Mike Rapoport Acked-by: Vlastimil Babka Cc: William Kucharski Cc: "Kirill A. Shutemov" Link: http://lkml.kernel.org/r/20200709202117.7216-1-willy@infradead.org Link: http://lkml.kernel.org/r/20200709202117.7216-2-willy@infradead.org Signed-off-by: Linus Torvalds

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41Z

Better describe what these functions do. Suggested-by: Linus Torvalds Signed-off-by: Christoph Hellwig Signed-off-by: Linus Torvalds