64 lines
2.8 KiB
Diff
64 lines
2.8 KiB
Diff
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From: Matthias Schiffer <mschiffer@universe-factory.net>
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Date: Mon, 4 Jan 2016 10:22:52 +0100
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Subject: kernel: fs, seq_file: fallback to vmalloc instead of oom kill processes
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diff --git a/target/linux/generic/patches-3.18/089-fs-seq_file-fallback-to-vmalloc-instead-of-oom-kill-.patch b/target/linux/generic/patches-3.18/089-fs-seq_file-fallback-to-vmalloc-instead-of-oom-kill-.patch
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new file mode 100644
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index 0000000..cad56f4
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--- /dev/null
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+++ b/target/linux/generic/patches-3.18/089-fs-seq_file-fallback-to-vmalloc-instead-of-oom-kill-.patch
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@@ -0,0 +1,53 @@
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+From 5cec38ac866bfb8775638e71a86e4d8cac30caae Mon Sep 17 00:00:00 2001
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+Message-Id: <5cec38ac866bfb8775638e71a86e4d8cac30caae.1451899087.git.mschiffer@universe-factory.net>
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+From: David Rientjes <rientjes@google.com>
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+Date: Fri, 12 Dec 2014 16:56:16 -0800
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+Subject: [PATCH] fs, seq_file: fallback to vmalloc instead of oom kill
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+ processes
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+
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+Since commit 058504edd026 ("fs/seq_file: fallback to vmalloc allocation"),
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+seq_buf_alloc() falls back to vmalloc() when the kmalloc() for contiguous
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+memory fails. This was done to address order-4 slab allocations for
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+reading /proc/stat on large machines and noticed because
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+PAGE_ALLOC_COSTLY_ORDER < 4, so there is no infinite loop in the page
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+allocator when allocating new slab for such high-order allocations.
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+
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+Contiguous memory isn't necessary for caller of seq_buf_alloc(), however.
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+Other GFP_KERNEL high-order allocations that are <=
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+PAGE_ALLOC_COSTLY_ORDER will simply loop forever in the page allocator and
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+oom kill processes as a result.
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+
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+We don't want to kill processes so that we can allocate contiguous memory
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+in situations when contiguous memory isn't necessary.
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+
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+This patch does the kmalloc() allocation with __GFP_NORETRY for high-order
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+allocations. This still utilizes memory compaction and direct reclaim in
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+the allocation path, the only difference is that it will fail immediately
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+instead of oom kill processes when out of memory.
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+
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+[akpm@linux-foundation.org: add comment]
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+Signed-off-by: David Rientjes <rientjes@google.com>
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+Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
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+Cc: Christoph Hellwig <hch@infradead.org>
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+Cc: Al Viro <viro@zeniv.linux.org.uk>
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+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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+---
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+ fs/seq_file.c | 6 +++++-
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+ 1 file changed, 5 insertions(+), 1 deletion(-)
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+
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+--- a/fs/seq_file.c
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++++ b/fs/seq_file.c
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+@@ -36,7 +36,11 @@ static void *seq_buf_alloc(unsigned long
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+ {
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+ void *buf;
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+
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+- buf = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
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++ /*
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++ * __GFP_NORETRY to avoid oom-killings with high-order allocations -
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++ * it's better to fall back to vmalloc() than to kill things.
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++ */
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++ buf = kmalloc(size, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
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+ if (!buf && size > PAGE_SIZE)
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+ buf = vmalloc(size);
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+ return buf;
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