From e47690d756a760579141560ded06ec1020dd85e8 Mon Sep 17 00:00:00 2001 From: Steven Price Date: Mon, 3 Feb 2020 17:36:42 -0800 Subject: x86: mm: avoid allocating struct mm_struct on the stack struct mm_struct is quite large (~1664 bytes) and so allocating on the stack may cause problems as the kernel stack size is small. Since ptdump_walk_pgd_level_core() was only allocating the structure so that it could modify the pgd argument we can instead introduce a pgd override in struct mm_walk and pass this down the call stack to where it is needed. Since the correct mm_struct is now being passed down, it is now also unnecessary to take the mmap_sem semaphore because ptdump_walk_pgd() will now take the semaphore on the real mm. [steven.price@arm.com: restore missed arm64 changes] Link: http://lkml.kernel.org/r/20200108145710.34314-1-steven.price@arm.com Link: http://lkml.kernel.org/r/20200108145710.34314-1-steven.price@arm.com Signed-off-by: Steven Price Reported-by: Stephen Rothwell Cc: Catalin Marinas Cc: Albert Ou Cc: Alexandre Ghiti Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: Arnd Bergmann Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Christian Borntraeger Cc: Dave Hansen Cc: David S. Miller Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: James Hogan Cc: James Morse Cc: Jerome Glisse Cc: "Liang, Kan" Cc: Mark Rutland Cc: Michael Ellerman Cc: Paul Burton Cc: Paul Mackerras Cc: Paul Walmsley Cc: Peter Zijlstra Cc: Ralf Baechle Cc: Russell King Cc: Thomas Gleixner Cc: Vasily Gorbik Cc: Vineet Gupta Cc: Will Deacon Cc: Zong Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/ptdump.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'mm/ptdump.c') diff --git a/mm/ptdump.c b/mm/ptdump.c index ad18a9839d6f..26208d0d03b7 100644 --- a/mm/ptdump.c +++ b/mm/ptdump.c @@ -122,14 +122,14 @@ static const struct mm_walk_ops ptdump_ops = { .pte_hole = ptdump_hole, }; -void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm) +void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm, pgd_t *pgd) { const struct ptdump_range *range = st->range; down_read(&mm->mmap_sem); while (range->start != range->end) { walk_page_range_novma(mm, range->start, range->end, - &ptdump_ops, st); + &ptdump_ops, pgd, st); range++; } up_read(&mm->mmap_sem); -- cgit v1.2.3-58-ga151