kernel/git/stable/linux.git/mm/util.c, branch linux-4.19.y

random: move randomize_page() into mm where it belongs

2022-06-25T09:49:12+00:00

commit 5ad7dd882e45d7fe432c32e896e2aaa0b21746ea upstream. randomize_page is an mm function. It is documented like one. It contains the history of one. It has the naming convention of one. It looks just like another very similar function in mm, randomize_stack_top(). And it has always been maintained and updated by mm people. There is no need for it to be in random.c. In the "which shape does not look like the other ones" test, pointing to randomize_page() is correct. So move randomize_page() into mm/util.c, right next to the similar randomize_stack_top() function. This commit contains no actual code changes. Cc: Andrew Morton Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman

mm: add kvfree_sensitive() for freeing sensitive data objects

2020-06-22T07:05:01+00:00

[ Upstream commit d4eaa2837851db2bfed572898bfc17f9a9f9151e ] For kvmalloc'ed data object that contains sensitive information like cryptographic keys, we need to make sure that the buffer is always cleared before freeing it. Using memset() alone for buffer clearing may not provide certainty as the compiler may compile it away. To be sure, the special memzero_explicit() has to be used. This patch introduces a new kvfree_sensitive() for freeing those sensitive data objects allocated by kvmalloc(). The relevant places where kvfree_sensitive() can be used are modified to use it. Fixes: 4f0882491a14 ("KEYS: Avoid false positive ENOMEM error on key read") Suggested-by: Linus Torvalds Signed-off-by: Waiman Long Signed-off-by: Andrew Morton Reviewed-by: Eric Biggers Acked-by: David Howells Cc: Jarkko Sakkinen Cc: James Morris Cc: "Serge E. Hallyn" Cc: Joe Perches Cc: Matthew Wilcox Cc: David Rientjes Cc: Uladzislau Rezki Link: http://lkml.kernel.org/r/20200407200318.11711-1-longman@redhat.com Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

mm: page_mapped: don't assume compound page is huge or THP

2019-01-16T21:04:36+00:00

commit 8ab88c7169b7fba98812ead6524b9d05bc76cf00 upstream. LTP proc01 testcase has been observed to rarely trigger crashes on arm64: page_mapped+0x78/0xb4 stable_page_flags+0x27c/0x338 kpageflags_read+0xfc/0x164 proc_reg_read+0x7c/0xb8 __vfs_read+0x58/0x178 vfs_read+0x90/0x14c SyS_read+0x60/0xc0 The issue is that page_mapped() assumes that if compound page is not huge, then it must be THP. But if this is 'normal' compound page (COMPOUND_PAGE_DTOR), then following loop can keep running (for HPAGE_PMD_NR iterations) until it tries to read from memory that isn't mapped and triggers a panic: for (i = 0; i < hpage_nr_pages(page); i++) { if (atomic_read(&page[i]._mapcount) >= 0) return true; } I could replicate this on x86 (v4.20-rc4-98-g60b548237fed) only with a custom kernel module [1] which: - allocates compound page (PAGEC) of order 1 - allocates 2 normal pages (COPY), which are initialized to 0xff (to satisfy _mapcount >= 0) - 2 PAGEC page structs are copied to address of first COPY page - second page of COPY is marked as not present - call to page_mapped(COPY) now triggers fault on access to 2nd COPY page at offset 0x30 (_mapcount) [1] https://github.com/jstancek/reproducers/blob/master/kernel/page_mapped_crash/repro.c Fix the loop to iterate for "1 << compound_order" pages. Kirrill said "IIRC, sound subsystem can producuce custom mapped compound pages". Link: http://lkml.kernel.org/r/c440d69879e34209feba21e12d236d06bc0a25db.1543577156.git.jstancek@redhat.com Fixes: e1534ae95004 ("mm: differentiate page_mapped() from page_mapcount() for compound pages") Signed-off-by: Jan Stancek Debugged-by: Laszlo Ersek Suggested-by: "Kirill A. Shutemov" Acked-by: Michal Hocko Acked-by: Kirill A. Shutemov Reviewed-by: David Hildenbrand Reviewed-by: Andrea Arcangeli Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

mm/util.c: improve kvfree() kerneldoc

2018-09-04T23:45:02+00:00

Scooped from an email from Matthew. Cc: Mike Rapoport Cc: Jonathan Corbet Cc: Matthew Wilcox Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/util: add kernel-doc for kvfree

2018-08-24T01:48:43+00:00

Link: http://lkml.kernel.org/r/1532626360-16650-3-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Reviewed-by: Andrew Morton Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/util: make strndup_user description a kernel-doc comment

2018-08-24T01:48:43+00:00

Patch series "memory management documentation updates", v3. Here are several updates to the mm documentation. Aside from really minor changes in the first three patches, the updates are: * move the documentation of kstrdup and friends to "String Manipulation" section * split memory management API into a separate .rst file * adjust formating of the GFP flags description and include it in the reference documentation. This patch (of 7): The description of the strndup_user function misses '*' character at the beginning of the comment to be proper kernel-doc. Add the missing character. Link: http://lkml.kernel.org/r/1532626360-16650-2-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport Reviewed-by: Andrew Morton Cc: Jonathan Corbet Cc: Matthew Wilcox Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: kvmalloc does not fallback to vmalloc for incompatible gfp flags

2018-06-08T00:34:38+00:00

kvmalloc warned about incompatible gfp_mask to catch abusers (mostly GFP_NOFS) with an intention that this will motivate authors of the code to fix those. Linus argues that this just motivates people to do even more hacks like if (gfp == GFP_KERNEL) kvmalloc else kmalloc I haven't seen this happening much (Linus pointed to bucket_lock special cases an atomic allocation but my git foo hasn't found much more) but it is true that we can grow those in future. Therefore Linus suggested to simply not fallback to vmalloc for incompatible gfp flags and rather stick with the kmalloc path. Link: http://lkml.kernel.org/r/20180601115329.27807-1-mhocko@kernel.org Signed-off-by: Michal Hocko Suggested-by: Linus Torvalds Cc: Tom Herbert Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'mm-rst' into docs-next

2018-04-16T20:25:08+00:00

Mike Rapoport says: These patches convert files in Documentation/vm to ReST format, add an initial index and link it to the top level documentation. There are no contents changes in the documentation, except few spelling fixes. The relatively large diffstat stems from the indentation and paragraph wrapping changes. I've tried to keep the formatting as consistent as possible, but I could miss some places that needed markup and add some markup where it was not necessary. [jc: significant conflicts in vm/hmm.rst]

docs/vm: rename documentation files to .rst

2018-04-16T20:18:15+00:00

Signed-off-by: Mike Rapoport Signed-off-by: Jonathan Corbet

mm/gup.c: document return value

2018-04-14T00:10:27+00:00

__get_user_pages_fast handles errors differently from get_user_pages_fast: the former always returns the number of pages pinned, the later might return a negative error code. Link: http://lkml.kernel.org/r/1522962072-182137-6-git-send-email-mst@redhat.com Signed-off-by: Michael S. Tsirkin Reviewed-by: Andrew Morton Cc: Kirill A. Shutemov Cc: Huang Ying Cc: Jonathan Corbet Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Thorsten Leemhuis Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds