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authorLinus Torvalds <torvalds@linux-foundation.org>2015-11-07 22:32:45 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2015-11-07 22:32:45 (GMT)
commitad804a0b2a769a0eed29015c53fe395449c09d13 (patch)
tree3f96dd15fe24705cd8244bdb8fb81a7195f6ea04 /Documentation/vm/balance
parentab9f2faf8f40604551336e5b0a18e0910a57b92c (diff)
parent5f2a2d5d423d5337a1392fa016ec23a8a4206006 (diff)
downloadlinux-ad804a0b2a769a0eed29015c53fe395449c09d13.tar.xz
Merge branch 'akpm' (patches from Andrew)
Merge second patch-bomb from Andrew Morton: - most of the rest of MM - procfs - lib/ updates - printk updates - bitops infrastructure tweaks - checkpatch updates - nilfs2 update - signals - various other misc bits: coredump, seqfile, kexec, pidns, zlib, ipc, dma-debug, dma-mapping, ... * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (102 commits) ipc,msg: drop dst nil validation in copy_msg include/linux/zutil.h: fix usage example of zlib_adler32() panic: release stale console lock to always get the logbuf printed out dma-debug: check nents in dma_sync_sg* dma-mapping: tidy up dma_parms default handling pidns: fix set/getpriority and ioprio_set/get in PRIO_USER mode kexec: use file name as the output message prefix fs, seqfile: always allow oom killer seq_file: reuse string_escape_str() fs/seq_file: use seq_* helpers in seq_hex_dump() coredump: change zap_threads() and zap_process() to use for_each_thread() coredump: ensure all coredumping tasks have SIGNAL_GROUP_COREDUMP signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() signal: turn dequeue_signal_lock() into kernel_dequeue_signal() signals: kill block_all_signals() and unblock_all_signals() nilfs2: fix gcc uninitialized-variable warnings in powerpc build nilfs2: fix gcc unused-but-set-variable warnings MAINTAINERS: nilfs2: add header file for tracing nilfs2: add tracepoints for analyzing reading and writing metadata files ...
Diffstat (limited to 'Documentation/vm/balance')
-rw-r--r--Documentation/vm/balance14
1 files changed, 8 insertions, 6 deletions
diff --git a/Documentation/vm/balance b/Documentation/vm/balance
index c46e68c..9645954 100644
--- a/Documentation/vm/balance
+++ b/Documentation/vm/balance
@@ -1,12 +1,14 @@
Started Jan 2000 by Kanoj Sarcar <kanoj@sgi.com>
-Memory balancing is needed for non __GFP_WAIT as well as for non
-__GFP_IO allocations.
+Memory balancing is needed for !__GFP_ATOMIC and !__GFP_KSWAPD_RECLAIM as
+well as for non __GFP_IO allocations.
-There are two reasons to be requesting non __GFP_WAIT allocations:
-the caller can not sleep (typically intr context), or does not want
-to incur cost overheads of page stealing and possible swap io for
-whatever reasons.
+The first reason why a caller may avoid reclaim is that the caller can not
+sleep due to holding a spinlock or is in interrupt context. The second may
+be that the caller is willing to fail the allocation without incurring the
+overhead of page reclaim. This may happen for opportunistic high-order
+allocation requests that have order-0 fallback options. In such cases,
+the caller may also wish to avoid waking kswapd.
__GFP_IO allocation requests are made to prevent file system deadlocks.