Commit 9c3ebeda authored by Liam R. Howlett's avatar Liam R. Howlett Committed by Andrew Morton
Browse files

mm/vma: track start and end for munmap in vma_munmap_struct 

Set the start and end address for munmap when the prev and next are
gathered.  This is needed to avoid incorrect addresses being used during
the vms_complete_munmap_vmas() function if the prev/next vma are expanded.

Add a new helper vms_complete_pte_clear(), which is needed later and will
avoid growing the argument list to unmap_region() beyond the 9 it already
has.

Link: https://lkml.kernel.org/r/20240830040101.822209-13-Liam.Howlett@oracle.com


Signed-off-by: default avatarLiam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: default avatarLorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Bert Karwatzki <spasswolf@web.de>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent d744f4ac

mm/vma.c

+25 −7
Original line number Diff line number Diff line
@@ -646,6 +646,26 @@ void vma_complete(struct vma_prepare *vp, 
		uprobe_mmap(vp->insert);

}



static void vms_complete_pte_clear(struct vma_munmap_struct *vms,

		struct ma_state *mas_detach, bool mm_wr_locked)

{

	struct mmu_gather tlb;



	/*

	 * We can free page tables without write-locking mmap_lock because VMAs

	 * were isolated before we downgraded mmap_lock.

	 */

	mas_set(mas_detach, 1);

	lru_add_drain();

	tlb_gather_mmu(&tlb, vms->mm);

	update_hiwater_rss(vms->mm);

	unmap_vmas(&tlb, mas_detach, vms->vma, vms->start, vms->end, vms->vma_count, mm_wr_locked);

	mas_set(mas_detach, 1);

	/* start and end may be different if there is no prev or next vma. */

	free_pgtables(&tlb, mas_detach, vms->vma, vms->unmap_start, vms->unmap_end, mm_wr_locked);

	tlb_finish_mmu(&tlb);

}



/*

 * vms_complete_munmap_vmas() - Finish the munmap() operation

 * @vms: The vma munmap struct
@@ -667,13 +687,7 @@ void vms_complete_munmap_vmas(struct vma_munmap_struct *vms, 
	if (vms->unlock)

		mmap_write_downgrade(mm);



	/*

	 * We can free page tables without write-locking mmap_lock because VMAs

	 * were isolated before we downgraded mmap_lock.

	 */

	mas_set(mas_detach, 1);

	unmap_region(mm, mas_detach, vms->vma, vms->prev, vms->next,

		     vms->start, vms->end, vms->vma_count, !vms->unlock);

	vms_complete_pte_clear(vms, mas_detach, !vms->unlock);

	/* Update high watermark before we lower total_vm */

	update_hiwater_vm(mm);

	/* Stat accounting */
@@ -745,6 +759,8 @@ int vms_gather_munmap_vmas(struct vma_munmap_struct *vms, 
			goto start_split_failed;

	}

	vms->prev = vma_prev(vms->vmi);

	if (vms->prev)

		vms->unmap_start = vms->prev->vm_end;



	/*

	 * Detach a range of VMAs from the mm. Using next as a temp variable as
@@ -805,6 +821,8 @@ int vms_gather_munmap_vmas(struct vma_munmap_struct *vms, 
	}



	vms->next = vma_next(vms->vmi);

	if (vms->next)

		vms->unmap_end = vms->next->vm_start;



#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)

	/* Make sure no VMAs are about to be lost. */

mm/vma.h

+6 −0
Original line number Diff line number Diff line
@@ -38,6 +38,8 @@ struct vma_munmap_struct { 
	struct list_head *uf;           /* Userfaultfd list_head */

	unsigned long start;            /* Aligned start addr (inclusive) */

	unsigned long end;              /* Aligned end addr (exclusive) */

	unsigned long unmap_start;      /* Unmap PTE start */

	unsigned long unmap_end;        /* Unmap PTE end */

	int vma_count;                  /* Number of vmas that will be removed */

	unsigned long nr_pages;         /* Number of pages being removed */

	unsigned long locked_vm;        /* Number of locked pages */
@@ -78,6 +80,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 
int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,

	       unsigned long start, unsigned long end, pgoff_t pgoff);



#ifdef CONFIG_MMU

/*

 * init_vma_munmap() - Initializer wrapper for vma_munmap_struct

 * @vms: The vma munmap struct
@@ -108,7 +111,10 @@ static inline void init_vma_munmap(struct vma_munmap_struct *vms, 
	vms->vma_count = 0;

	vms->nr_pages = vms->locked_vm = vms->nr_accounted = 0;

	vms->exec_vm = vms->stack_vm = vms->data_vm = 0;

	vms->unmap_start = FIRST_USER_ADDRESS;

	vms->unmap_end = USER_PGTABLES_CEILING;

}

#endif



int vms_gather_munmap_vmas(struct vma_munmap_struct *vms,

		struct ma_state *mas_detach);