From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Fri, 16 Dec 2022 17:32:27 +0100 Subject: [PATCH] mm, mremap: fix mremap() expanding vma with addr inside vma MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 6f12be792fde994ed934168f93c2a0d2a0cf0bc5 upstream. 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. Link: https://lkml.kernel.org/r/20221216163227.24648-1-vbabka@suse.cz Reported-by: Jiri Slaby Link: https://bugzilla.suse.com/show_bug.cgi?id=1206359 Fixes: ca3d76b0aa80 ("mm: add merging after mremap resize") Signed-off-by: Vlastimil Babka Cc: Jakub Matěna Cc: "Kirill A . Shutemov" Cc: Liam Howlett Cc: Matthew Wilcox Cc: Mel Gorman Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 4d528dab403ba45db24769f5e5a9514ab0890351) Signed-off-by: Thomas Lamprecht --- 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)) {