65 lines
2.4 KiB
Diff
65 lines
2.4 KiB
Diff
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From: Tejun Heo <tj <at> kernel.org>
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Subject: [PATCH 3.4-rc3] memblock: memblock should be able to handle zero length operations
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Newsgroups: gmane.linux.kernel, gmane.linux.kernel.stable
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Date: 2012-04-20 15:31:34 GMT (2 days, 14 hours and 59 minutes ago)
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24aa07882b "memblock, x86: Replace memblock_x86_reserve/free_range()
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with generic ones" replaced x86 specific memblock operations with the
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generic ones; unfortunately, it lost zero length operation handling in
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the process making the kernel panic if somebody tries to reserve zero
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length area.
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There isn't much to be gained by being cranky to zero length
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operations and panicking is almost the worst response. Drop the
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BUG_ON() in memblock_reserve() and update
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memblock_add_region/isolate_range() so that all zero length operations
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are handled as noops.
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Signed-off-by: Tejun Heo <tj <at> kernel.org>
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Cc: stable <at> vger.kernel.org
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Reported-by: Valere Monseur <valere.monseur <at> ymail.com>
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Bisected-by: Joseph Freeman <jfree143dev <at> gmail.com>
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Tested-by: Joseph Freeman <jfree143dev <at> gmail.com>
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Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=43098
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---
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This is causing early panics if anyone tries to reserve zero len area,
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which unfortunately isn't too uncommon depending on BIOS. The fix is
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fairly safe. Unsure which tree it should go through. Cc'ing Linus
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and Ingo.
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Thanks.
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mm/memblock.c | 7 ++++++-
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1 file changed, 6 insertions(+), 1 deletion(-)
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diff --git a/mm/memblock.c b/mm/memblock.c
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index 99f2855..a44eab3 100644
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--- a/mm/memblock.c
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+++ b/mm/memblock.c
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@@ -330,6 +330,9 @@ static int __init_memblock memblock_add_region(struct memblock_type *type,
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phys_addr_t end = base + memblock_cap_size(base, &size);
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int i, nr_new;
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+ if (!size)
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+ return 0;
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+
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/* special case for empty array */
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if (type->regions[0].size == 0) {
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WARN_ON(type->cnt != 1 || type->total_size);
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@@ -430,6 +433,9 @@ static int __init_memblock memblock_isolate_range(struct memblock_type *type,
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*start_rgn = *end_rgn = 0;
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+ if (!size)
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+ return 0;
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+
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/* we'll create at most two more regions */
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while (type->cnt + 2 > type->max)
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if (memblock_double_array(type) < 0)
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@@ -514,7 +520,6 @@ int __init_memblock memblock_reserve(phys_addr_t base, phys_addr_t size)
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(unsigned long long)base,
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(unsigned long long)base + size,
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(void *)_RET_IP_);
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- BUG_ON(0 == size);
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return memblock_add_region(_rgn, base, size, MAX_NUMNODES);
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}
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