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Commit 2fbfac4e authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

thp+memcg-numa: fix BUG at include/linux/mm.h:370! 



THP's collapse_huge_page() has an understandable but ugly difference
in when its huge page is allocated: inside if NUMA but outside if not.
It's hardly surprising that the memcg failure path forgot that, freeing
the page in the non-NUMA case, then hitting a VM_BUG_ON in get_page()
(or even worse, using the freed page).

Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c44ed965

mm/huge_memory.c

+5 −1
Original line number Diff line number Diff line
@@ -1762,6 +1762,10 @@ static void collapse_huge_page(struct mm_struct *mm, 
#ifndef CONFIG_NUMA

	VM_BUG_ON(!*hpage);

	new_page = *hpage;

	if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {

		up_read(&mm->mmap_sem);

		return;

	}

#else

	VM_BUG_ON(*hpage);

	/*
@@ -1781,12 +1785,12 @@ static void collapse_huge_page(struct mm_struct *mm, 
		*hpage = ERR_PTR(-ENOMEM);

		return;

	}

#endif

	if (unlikely(mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))) {

		up_read(&mm->mmap_sem);

		put_page(new_page);

		return;

	}

#endif



	/* after allocating the hugepage upgrade to mmap_sem write mode */

	up_read(&mm->mmap_sem);