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Fix arena chunk purge/dealloc race conditions.

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Fix arena_chunk_dealloc() to put the new spare in a consistent state before
dropping the arena mutex to deallocate the previous spare.

Fix arena_run_dalloc() to insert a newly dirtied chunk into the
chunks_dirty list before potentially deallocating the chunk, so that dirty
page accounting is self-consistent.
This commit is contained in:
Jason Evans 2010-04-13 20:53:21 -07:00
parent 5065156f3f
commit 8d4203c72d
1 changed files with 31 additions and 25 deletions
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56
jemalloc/src/arena.c
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@ -470,23 +470,6 @@ arena_chunk_dealloc(arena_t *arena, arena_chunk_t *chunk)
{ {
arena_avail_tree_t *runs_avail; arena_avail_tree_t *runs_avail;
while (arena->spare != NULL) {
arena_chunk_t *spare = arena->spare;
arena->spare = NULL;
if (spare->dirtied) {
ql_remove(&chunk->arena->chunks_dirty, spare,
link_dirty);
arena->ndirty -= spare->ndirty;
}
malloc_mutex_unlock(&arena->lock);
chunk_dealloc((void *)spare, chunksize);
malloc_mutex_lock(&arena->lock);
#ifdef JEMALLOC_STATS
arena->stats.mapped -= chunksize;
#endif
}
/* /*
* Remove run from the appropriate runs_avail_* tree, so that the arena * Remove run from the appropriate runs_avail_* tree, so that the arena
* does not use it. * does not use it.
@ -499,7 +482,23 @@ arena_chunk_dealloc(arena_t *arena, arena_chunk_t *chunk)
arena_avail_tree_remove(runs_avail, arena_avail_tree_remove(runs_avail,
&chunk->map[arena_chunk_header_npages]); &chunk->map[arena_chunk_header_npages]);
arena->spare = chunk; if (arena->spare != NULL) {
arena_chunk_t *spare = arena->spare;
arena->spare = chunk;
if (spare->dirtied) {
ql_remove(&chunk->arena->chunks_dirty, spare,
link_dirty);
arena->ndirty -= spare->ndirty;
}
malloc_mutex_unlock(&arena->lock);
chunk_dealloc((void *)spare, chunksize);
malloc_mutex_lock(&arena->lock);
#ifdef JEMALLOC_STATS
arena->stats.mapped -= chunksize;
#endif
} else
arena->spare = chunk;
} }
static arena_run_t * static arena_run_t *
@ -925,6 +924,18 @@ arena_run_dalloc(arena_t *arena, arena_run_t *run, bool dirty)
/* Insert into runs_avail, now that coalescing is complete. */ /* Insert into runs_avail, now that coalescing is complete. */
arena_avail_tree_insert(runs_avail, &chunk->map[run_ind]); arena_avail_tree_insert(runs_avail, &chunk->map[run_ind]);
if (dirty) {
/*
* Insert into chunks_dirty before potentially calling
* arena_chunk_dealloc(), so that chunks_dirty and
* arena->ndirty are consistent.
*/
if (chunk->dirtied == false) {
ql_tail_insert(&arena->chunks_dirty, chunk, link_dirty);
chunk->dirtied = true;
}
}
/* /*
* Deallocate chunk if it is now completely unused. The bit * Deallocate chunk if it is now completely unused. The bit
* manipulation checks whether the first run is unallocated and extends * manipulation checks whether the first run is unallocated and extends
@ -935,19 +946,14 @@ arena_run_dalloc(arena_t *arena, arena_run_t *run, bool dirty)
arena_chunk_dealloc(arena, chunk); arena_chunk_dealloc(arena, chunk);
/* /*
* It is okay to do dirty page processing even if the chunk was * It is okay to do dirty page processing here even if the chunk was
* deallocated above, since in that case it is the spare. Waiting * deallocated above, since in that case it is the spare. Waiting
* until after possible chunk deallocation to do dirty processing * until after possible chunk deallocation to do dirty processing
* allows for an old spare to be fully deallocated, thus decreasing the * allows for an old spare to be fully deallocated, thus decreasing the
* chances of spuriously crossing the dirty page purging threshold. * chances of spuriously crossing the dirty page purging threshold.
*/ */
if (dirty) { if (dirty)
if (chunk->dirtied == false) {
ql_tail_insert(&arena->chunks_dirty, chunk, link_dirty);
chunk->dirtied = true;
}
arena_maybe_purge(arena); arena_maybe_purge(arena);
}
} }
static void static void