Messages in this thread Patch in this message | | | From | Vlastimil Babka <> | Subject | [PATCH for v6.1 regression] mm, mremap: fix mremap() expanding vma with addr inside vma | Date | Fri, 16 Dec 2022 17:32:27 +0100 |
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Since 6.1 we have noticed random rpm install failures that were tracked to mremap() returning -ENOMEM and to commit ca3d76b0aa80 ("mm: add merging after mremap resize").
The problem occurs when mremap() expands a VMA in place, but using an starting address that's not vma->vm_start, but somewhere in the middle. The extension_pgoff calculation introduced by the commit is wrong in that case, so vma_merge() fails due to pgoffs not being compatible. Fix the calculation.
By the way it seems that the situations, where rpm now expands a vma from the middle, were made possible also due to that commit, thanks to the improved vma merging. Yet it should work just fine, except for the buggy calculation.
Reported-by: Jiri Slaby <jirislaby@kernel.org> Link: https://bugzilla.suse.com/show_bug.cgi?id=1206359 Fixes: ca3d76b0aa80 ("mm: add merging after mremap resize") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jakub Matěna <matenajakub@gmail.com> Cc: <stable@vger.kernel.org> Cc: "Kirill A . Shutemov" <kirill@shutemov.name> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> --- Hi, this fixes a regression in 6.1 so please process ASAP so that stable 6.1.y can get the fix.
mm/mremap.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/mremap.c b/mm/mremap.c index e465ffe279bb..fe587c5d6591 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1016,7 +1016,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, long pages = (new_len - old_len) >> PAGE_SHIFT; unsigned long extension_start = addr + old_len; unsigned long extension_end = addr + new_len; - pgoff_t extension_pgoff = vma->vm_pgoff + (old_len >> PAGE_SHIFT); + pgoff_t extension_pgoff = vma->vm_pgoff + + ((extension_start - vma->vm_start) >> PAGE_SHIFT); if (vma->vm_flags & VM_ACCOUNT) { if (security_vm_enough_memory_mm(mm, pages)) { -- 2.38.1
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