mm: fix dirty_bytes/dirty_background_bytes sysctls on 64bit arches (fc3501d4) · Commits · 戴 / test

We need to pass an unsigned long as the minimum, because it gets casted to an unsigned long in the sysctl handler. If we pass an int, we'll access four more bytes on 64bit arches, resulting in a random minimum value. [rientjes@google.com: fix type of `old_bytes'] Signed-off-by:

Sven Wegener <sven.wegener@stealer.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Dave Chinner <david@fromorbit.com> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: David Rientjes <rientjes@google.com> Signed-off-by:

David Rientjes <rientjes@google.com> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

kernel/sysctl.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -101,6 +101,7 @@ static int two = 2;

		static int zero;
		static int one = 1;
		static unsigned long one_ul = 1;
		static int one_hundred = 100;

		/* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */
		@@ -974,7 +975,7 @@ static struct ctl_table vm_table[] = {
		.mode = 0644,
		.proc_handler = &dirty_background_bytes_handler,
		.strategy = &sysctl_intvec,
		.extra1 = &one,
		.extra1 = &one_ul,
		},
		{
		.ctl_name = VM_DIRTY_RATIO,
		@@ -995,7 +996,7 @@ static struct ctl_table vm_table[] = {
		.mode = 0644,
		.proc_handler = &dirty_bytes_handler,
		.strategy = &sysctl_intvec,
		.extra1 = &one,
		.extra1 = &one_ul,
		},
		{
		.procname = "dirty_writeback_centisecs",

mm/page-writeback.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -209,7 +209,7 @@ int dirty_bytes_handler(struct ctl_table *table, int write,
		struct file filp, void __user buffer, size_t *lenp,
		loff_t *ppos)
		{
		int old_bytes = vm_dirty_bytes;
		unsigned long old_bytes = vm_dirty_bytes;
		int ret;

		ret = proc_doulongvec_minmax(table, write, filp, buffer, lenp, ppos);

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