* Re: [RFC PATCH] mm/vmalloc: make sure to traverse from the beginning when overflow occur [not found] <20200412143803.43931-1-fishland@aliyun.com> @ 2020-04-13 15:02 ` Dave Hansen 2020-04-14 19:02 ` Uladzislau Rezki 0 siblings, 1 reply; 2+ messages in thread From: Dave Hansen @ 2020-04-13 15:02 UTC (permalink / raw) To: Liu Song, gregkh, jroedel, dave.hansen, tglx Cc: linux-mm, linux-kernel, liu.song11 On 4/12/20 7:38 AM, Liu Song wrote: > If overflow, should ensure that "free_vmap_cache" is set to NULL, > so as to ensure that it can be traversed from the beginning. This changelog is a bit sparse. Does this fix a demonstrated problem? Or was it just discovered via code review and assumed to help a theoretical problem? Which tree is it against? 'free_vmap_cache' doesn't show up in Linus's tree. > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d8e877365f9f..2638a20d36ce 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -441,7 +441,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, > if (!free_vmap_cache || > size < cached_hole_size || > vstart < cached_vstart || > - align < cached_align) { > + align < cached_align || purged) { > nocache: > cached_hole_size = 0; > free_vmap_cache = NULL; Is 'purged' the right way to do this? There is a path through the overflow code that also sets purged=0. Does 'free_vmap_cache' *not* need to get reset in that case? It also seems more natural to me that the code mucking with the rbtree would be the one to reset the cache. ^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [RFC PATCH] mm/vmalloc: make sure to traverse from the beginning when overflow occur 2020-04-13 15:02 ` [RFC PATCH] mm/vmalloc: make sure to traverse from the beginning when overflow occur Dave Hansen @ 2020-04-14 19:02 ` Uladzislau Rezki 0 siblings, 0 replies; 2+ messages in thread From: Uladzislau Rezki @ 2020-04-14 19:02 UTC (permalink / raw) To: Dave Hansen, Liu Song Cc: Liu Song, gregkh, jroedel, dave.hansen, tglx, linux-mm, linux-kernel, liu.song11@zte.com.cnhange-folder>? On Mon, Apr 13, 2020 at 08:02:49AM -0700, Dave Hansen wrote: > On 4/12/20 7:38 AM, Liu Song wrote: > > If overflow, should ensure that "free_vmap_cache" is set to NULL, > > so as to ensure that it can be traversed from the beginning. > > This changelog is a bit sparse. > > Does this fix a demonstrated problem? Or was it just discovered via > code review and assumed to help a theoretical problem? > > Which tree is it against? 'free_vmap_cache' doesn't show up in Linus's > tree. > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index d8e877365f9f..2638a20d36ce 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -441,7 +441,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, > > if (!free_vmap_cache || > > size < cached_hole_size || > > vstart < cached_vstart || > > - align < cached_align) { > > + align < cached_align || purged) { > > nocache: > > cached_hole_size = 0; > > free_vmap_cache = NULL; > > We do not have such code since 5.2 kernel or so, nor things like cached_hole_size, free_vmap_cache and so on. It was totally reworked. -- Vlad Rezki ^ permalink raw reply [flat|nested] 2+ messages in thread
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2020-04-13 15:02 ` [RFC PATCH] mm/vmalloc: make sure to traverse from the beginning when overflow occur Dave Hansen
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