Commit 064d9efe authored by Nishanth Aravamudan's avatar Nishanth Aravamudan Committed by Linus Torvalds
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hugetlb: fix overcommit locking 



proc_doulongvec_minmax() calls copy_to_user()/copy_from_user(), so we can't
hold hugetlb_lock over the call.  Use a dummy variable to store the sysctl
result, like in hugetlb_sysctl_handler(), then grab the lock to update
nr_overcommit_huge_pages.

Signed-off-by: default avatarNishanth Aravamudan <nacc@us.ibm.com>
Reported-by: default avatarMiles Lane <miles.lane@gmail.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 2695a14d

include/linux/hugetlb.h

+1 −1
Original line number Diff line number Diff line
@@ -33,8 +33,8 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to); 
void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);



extern unsigned long max_huge_pages;

extern unsigned long sysctl_overcommit_huge_pages;

extern unsigned long hugepages_treat_as_movable;

extern unsigned long nr_overcommit_huge_pages;

extern const unsigned long hugetlb_zero, hugetlb_infinity;

extern int sysctl_hugetlb_shm_group;

kernel/sysctl.c

+2 −2
Original line number Diff line number Diff line
@@ -978,8 +978,8 @@ static struct ctl_table vm_table[] = { 
	{

		.ctl_name	= CTL_UNNUMBERED,

		.procname	= "nr_overcommit_hugepages",

		.data		= &nr_overcommit_huge_pages,

		.maxlen		= sizeof(nr_overcommit_huge_pages),

		.data		= &sysctl_overcommit_huge_pages,

		.maxlen		= sizeof(sysctl_overcommit_huge_pages),

		.mode		= 0644,

		.proc_handler	= &hugetlb_overcommit_handler,

	},

mm/hugetlb.c

+4 −2
Original line number Diff line number Diff line
@@ -24,14 +24,15 @@ 
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;

static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;

static unsigned long surplus_huge_pages;

static unsigned long nr_overcommit_huge_pages;

unsigned long max_huge_pages;

unsigned long sysctl_overcommit_huge_pages;

static struct list_head hugepage_freelists[MAX_NUMNODES];

static unsigned int nr_huge_pages_node[MAX_NUMNODES];

static unsigned int free_huge_pages_node[MAX_NUMNODES];

static unsigned int surplus_huge_pages_node[MAX_NUMNODES];

static gfp_t htlb_alloc_mask = GFP_HIGHUSER;

unsigned long hugepages_treat_as_movable;

unsigned long nr_overcommit_huge_pages;

static int hugetlb_next_nid;



/*
@@ -609,8 +610,9 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write, 
			struct file *file, void __user *buffer,

			size_t *length, loff_t *ppos)

{

	spin_lock(&hugetlb_lock);

	proc_doulongvec_minmax(table, write, file, buffer, length, ppos);

	spin_lock(&hugetlb_lock);

	nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;

	spin_unlock(&hugetlb_lock);

	return 0;

}

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