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 --- include/linux/pagewalk.h | 3 +++ include/linux/ptdump.h | 2 +- 2 files changed, 4 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/linux/pagewalk.h b/include/linux/pagewalk.h index 745a654c6ea7..b1cb6b753abb 100644 --- a/include/linux/pagewalk.h +++ b/include/linux/pagewalk.h @@ -74,6 +74,7 @@ enum page_walk_action { * mm_walk - walk_page_range data * @ops: operation to call during the walk * @mm: mm_struct representing the target process of page table walk + * @pgd: pointer to PGD; only valid with no_vma (otherwise set to NULL) * @vma: vma currently walked (NULL if walking outside vmas) * @action: next action to perform (see enum page_walk_action) * @no_vma: walk ignoring vmas (vma will always be NULL) @@ -84,6 +85,7 @@ enum page_walk_action { struct mm_walk { const struct mm_walk_ops *ops; struct mm_struct *mm; + pgd_t *pgd; struct vm_area_struct *vma; enum page_walk_action action; bool no_vma; @@ -95,6 +97,7 @@ int walk_page_range(struct mm_struct *mm, unsigned long start, void *private); int walk_page_range_novma(struct mm_struct *mm, unsigned long start, unsigned long end, const struct mm_walk_ops *ops, + pgd_t *pgd, void *private); int walk_page_vma(struct vm_area_struct *vma, const struct mm_walk_ops *ops, void *private); diff --git a/include/linux/ptdump.h b/include/linux/ptdump.h index b28f3f2acf90..a67065c403c3 100644 --- a/include/linux/ptdump.h +++ b/include/linux/ptdump.h @@ -17,6 +17,6 @@ struct ptdump_state { const struct ptdump_range *range; }; -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); #endif /* _LINUX_PTDUMP_H */ -- cgit