Messages in this thread | | | Date | Mon, 23 Nov 2015 12:14:00 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH v2] zram: Prevent page allocation failure during zcomp_strm_alloc |
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Hello,
On (11/23/15 11:15), Minchan Kim wrote: [..] > > static void *zcomp_lz4_create(void) > > { > > - return kzalloc(LZ4_MEM_COMPRESS, GFP_KERNEL); > > + void *ret; > > + > > + ret = kzalloc(LZ4_MEM_COMPRESS, > > + __GFP_NORETRY|__GFP_NOWARN|__GFP_NOMEMALLOC); > > + if (!ret) > > + ret = vzalloc(LZ4_MEM_COMPRESS); > > One thing I feel bad smell is that call vzalloc with GFP_KERNEL. > This function can be called in direct reclaim path with holding > fs lock and GFP_KERNEL can enter recursive reclaim path so > lockdep would complain theoretically if I don't miss something. >
yes, GFP_KERNEL looks a bit fragile to me too. And may be zcomp_strm_alloc() and comp->backend->create() deserve GFP_NOFS. I believe I sent a patch doing this a while ago: https://lkml.org/lkml/2015/6/16/465
> If it is true, we should fix several allocation flags in > zcomp_strm_alloc. I just want to record this warning for the future > in this thread so someone who is finding for the contribution > material will prove and fix it. :)
I can re-send the patch.
And, in case if you missed it, what's your opinion on the idea of reducing ->max_strm if we can't allocate new streams. Here: http://marc.info/?l=linux-kernel&m=144798049429861
-ss
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